Subsequent Events [Abstract] Subsequent Event Subsequent Events [Text Block] Equity [Abstract] Distributions Made to Limited Partner, by Distribution Distributions Made to Limited Partner, by Distribution [Table Text Block] New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Recent Accounting Pronouncements Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Regulatory Assets and Liabilities Disclosure [Abstract] Schedule of Regulatory Assets [Table] Schedule of Regulatory Assets [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Predecessor Predecessor [Member] Regulatory Asset [Axis] Regulatory Asset [Axis] Regulatory Asset [Domain] Regulatory Asset [Domain] Unrecognized Pension Benefit And Other Postretirement Benefit Costs Unrecognized Pension Benefit And Other Postretirement Benefit Costs [Member] Unrecognized Pension Benefit And Other Postretirement Benefit Costs [Member] Other Postretirement Costs Other Postretirement Costs [Member] Other Postretirement Costs [Member] Deferred Taxes on AFUDC Equity Deferred Taxes on AFUDC Equity [Member] Deferred Taxes on AFUDC Equity [Member] Other Assets Other Assets [Member] Regulatory Assets [Line Items] Regulatory Assets [Line Items] Total Regulatory Assets Regulatory Assets Pension and Other Postretirement Benefit Expense [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans [Domain] Defined Benefit Plan and Other Postretirement Benefit Plan [Domain] Defined Benefit Plan by Plan Asset Categories [Axis] Defined Benefit Plan, Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Defined Benefit Plan, Fair Value of Plan Assets by Measurement [Axis] Fair Value, Hierarchy [Axis] Fair Value Plan Asset Measurement [Domain] Fair Value Hierarchy [Domain] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Effect on service and interest components of net periodic cost, 1% point increase Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components Effect on service and interest components of net periodic cost, 1% point decrease Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components Effect on accumulated postretirement benefit obligation, 1% point increase Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation Effect on accumulated postretirement benefit obligation, 1% point decrease Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation Statement [Table] Statement [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Regulatory Assets and Liabilities [Member] Regulatory Assets and Liabilities [Member] Regulatory Assets and Liabilities [Member] Pension Plan Pension Plan [Member] Other Postretirement Benefits Other Postretirement Benefit Plan [Member] Statement [Line Items] Statement [Line Items] Net actuarial (gain)/loss Defined Benefit Plan, Actuarial Gain (Loss) Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Less: amortization of net actuarial (gain) loss Defined Benefit Plan, Amortization of Gains (Losses) Total Recognized in Other Comprehensive Income or Regulatory Asset or Liability Other changes recognized in other comprehensive income or regulatory asset or liability Other changes recognized in other comprehensive income or regulatory asset or liability Amount Recognized in Net Periodic Benefits Cost and Other Comprehensive Income or Regulatory Asset or Liability Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Or Regulatory Asset Or Liability Change in Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Or Regulatory Asset Or Liability Organization, Consolidation and Presentation of Financial Statements [Abstract] Beginning Balance Capitalized Exploratory Well Costs Additions Pending the Determination of Proved Reserves Capitalized Exploratory Well Cost, Additions Pending Determination of Proved Reserves Reclassification of Proved Reserves Reclassification to Well, Facilities, and Equipment Based on Determination of Proved Reserves Ending Balance Variable Interest Entities And Equity Investments [Abstract] Variable Interest Entities and Equity Investments. Equity Method Investments Schedule of Ownership Percentage Equity Method Investments Schedule of Ownership Percentage [Table Text Block] Equity Method Investments Schedule of Ownership Percentage [Table Text Block] Schedule Of Equity Method Investments Equity Method Investments [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Other Commitments And Contingencies Commitments and Contingencies Disclosure [Text Block] Other Nonoperating Income (Expense) [Abstract] Schedule Of Other, Net Schedule of Other Nonoperating Income (Expense) [Table Text Block] Statement of Stockholders' Equity [Abstract] Partner Type [Axis] Partner Type [Axis] Partner Type of Partners' Capital Account, Name [Domain] Partner Type of Partners' Capital Account, Name [Domain] Limited Partner Limited Partner [Member] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Common Units Common Units [Member] Common Units [Member] Subordinated Units Subordinated Units [Member] Subordinated Units [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Parent Parent [Member] Noncontrolling Interest Noncontrolling Interest [Member] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Beginning Balance Partners' Capital, Including Portion Attributable to Noncontrolling Interest Net Income (Loss) Attributable to Parent Net Income (Loss) Attributable to Parent Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Partners' Capital Account, Distributions Partners' Capital Account, Distributions Net Transfers (To) From Parent Net Transfers (To) From Parent Net Transfers (To) From Parent Net Income Income (Loss), Including Portion Attributable to Noncontrolling Interest Total comprehensive income Other Comprehensive Income (Loss), Net of Tax Contribution of capital from parent Partners' Capital Account, Contributions Predecessor Net Liabilities Not Assumed By Subsidiary Partners Capital Predecessor Net Liabilities Not Assumed By Subsidiary Partners Capital Predecessor Net Liabilities Not Assumed By Subsidiary Contributed/Noncontributed Net Parent Investment Adjustments Contributed/Noncontributed Net Parent Investment Adjustments Contributed/Noncontributed Net Parent Investment Adjustments Allocation of Net Investment to Unitholders Allocation of Net Investment to Unitholders Allocation of Net Investment to Unitholders Allocation of Accumulated Other Comprehensive Loss To Noncontrolling Interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Net proceeds from IPO Partners' Capital Account, Public Sale of Units Net of Offering Costs Purchase of additional interest in Columbia OpCo Noncontrolling Interest, Increase from Subsidiary Equity Issuance Distribution to the noncontrolling interest in Columbia OpCo Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Limited Partners' Capital Account, Distribution Amount Limited Partners' Capital Account, Distribution Amount Ending Balance Domestic Equities [Member] Domestic Equities [Member] Domestic Equities [Member] International Equities [Member] International Equities [Member] International Equities [Member] Fixed Income [Member] Debt Securities [Member] Real Estate/Private Equity/Hedge Funds [Member] Real Estate And Private Equity And Hedge Funds [Member] Real Estate And Private Equity And Hedge Funds [Member] Cash/Other [Member] Cash and Cash Equivalents [Member] Percentage of total asset Defined Benefit Plan Target Allocation Percentage Of Total Assets Defined Benefit Plan Target Allocation Percentage Of Total Assets Fair value of asset Defined Benefit Plan, Fair Value of Plan Assets Other Comprehensive Income (Loss), Tax [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Gains and Losses on Cash Flow Hedges Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Pension and OPEB Items Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Gains and Losses on Cash Flow Hedges Attributable to Noncontrolling Interest Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member] Pension and OPEB Items Attributable to Noncontrolling Interest [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest [Member] AOCI Attributable to Noncontrolling Interest AOCI Attributable to Noncontrolling Interest [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Beginning Balance Accumulated Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Partners Capital Predecessor Net Liabilities Not Assumed By Subsidiary Ending Balance Initial Public Offering [Abstract] Initial Public Offering [Abstract] Change From Net Income Attributable to the Partnership and Transfers to Noncontrolling Interest Change From Net Income Attributable to the Partnership and Transfers to Noncontrolling Interest [Table Text Block] Change From Net Income Attributable to the Partnership and Transfers to Noncontrolling Interest Regulatory Assets Schedule of Regulatory Assets [Table Text Block] Regulatory Liabilities Schedule of Regulatory Liabilities [Table Text Block] Benefit obligation at beginning of year Defined Benefit Plan, Benefit Obligation Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Plan participants' contributions Defined Benefit Plan, Contributions by Plan Participants Actuarial loss (gain) Benefits paid Defined Benefit Plan, Benefits Paid Estimated benefits paid by incurred subsidy Defined Benefit Plan, Estimated Benefits Paid By Incurred Subsidy Defined Benefit Plan, Estimated Benefits Paid By Incurred Subsidy Defined Benefit Plans, Contributed/Noncontributed Projected Benefit Obligation Defined Benefit Plans, Contributed/Noncontributed Projected Benefit Obligation Defined Benefit Plans, Contributed/Noncontributed Projected Benefit Obligation Projected benefit obligation at end of year Fair value of plan assets at beginning of year Defined Benefit Plan, Fair Value of Plan Assets1 Defined Benefit Plan, Fair Value of Plan Assets Fair value of plan assets at beginning of year Actual return on plan assets Defined Benefit Plan, Actual Return on Plan Assets Employer contributions Defined Benefit Plan, Contributions by Employer Defined Benefit Plans, Contributed And Noncontributed Plan Assets Defined Benefit Plans, Contributed And Noncontributed Plan Assets Defined Benefit Plans, Contributed/Noncontributed Plan Assets Fair value of plan assets at end of year Funded Status at end of year Defined Benefit Plan, Funded Status of Plan Noncurrent assets Defined Benefit Plan, Assets for Plan Benefits, Noncurrent Current liabilities Pension and Other Postretirement Defined Benefit Plans, Current Liabilities Noncurrent liabilities Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Net amount recognized at end of year Defined Benefit Plan, Amounts Recognized in Balance Sheet Unrecognized prior service cost Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax Unrecognized actuarial loss Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Or Regulatory Asset Or Liability DefinedBenefitPlanRecognizedInAccumulatedOtherComprehensiveIncomeNetGainsOrLossesBeforeIncomeTaxOrRegulatoryAssetsOrLiabilities Defined Benefit Plan Recognized In Accumulated Other Comprehensive Income Net Gains Or Losses Before Income Tax Or Regulatory Assets Or Liabilities Fair Value Disclosures [Abstract] Carrying Amount And Estimated Fair Values Of Financial Instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Statement of Comprehensive Income [Abstract] Scenario [Axis] Net unrealized gain on cash flow hedges Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Unrecognized pension and OPEB costs Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Other Comprehensive Income, Net of Tax and Transaction Adjustments Other Comprehensive Income, Net of Tax and Transaction Adjustments Other Comprehensive Income, Net of Tax and Transaction Adjustments Total comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Comprehensive income attributable to noncontrolling interest subsequent to IPO Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Comprehensive income attributable to limited partners subsequent to IPO Comprehensive Income (Loss), Net of Tax, Attributable to Limited Partners Comprehensive Income (Loss), Net of Tax, Attributable to Limited Partners Comprehensive Income (Loss): Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Earnings Per Share [Abstract] Schedule Of Earnings Per Unit [Table] Schedule Of Earnings Per Unit [Table] Schedule Of Earnings Per Unit [Table] Other Ownership Interests Name [Axis] Other Ownership Interests Name [Axis] Other Ownership Interests, Name [Domain] Other Ownership Interests, Name [Domain] Incentive Distribution Rights Incentive Distribution Rights [Member] Incentive Distribution Rights Schedule Of Earnings Per Unit [Line Items] Schedule Of Earnings Per Unit [Line Items] [Line Items] for Schedule Of Earnings Per Unit [Table] Distribution Made to Limited Partner, Cash Distributions Declared Distribution Made to Limited Partner, Cash Distributions Declared Incentive Distribution, Distribution Incentive Distribution, Distribution Partners' Capital Account, Distributions Cash Distributions Declared Total distributions to each interest (i.e., general partner, limited partners and incentive distribution rights). Undistributed Earnings, Basic Undistributed Earnings, Basic Net Income (Loss) Allocated to Limited Partners Net Income (Loss) Allocated to Limited Partners Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted Average Number of Shares Outstanding, Basic and Diluted Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax Components of Accumulated Other Comprehensive Income (Loss) [Abstract] Components of Accumulated Other Comprehensive Income (Loss) [Abstract] Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Timing [Axis] Timing [Axis] Timing [Axis] Timing [Domain] Timing [Domain] [Domain] for Timing [Axis] Annualized [Member] Annualized [Member] Annualized [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Distribution Made to Limited Partner, Distributions Paid, Per Unit Distribution Made to Limited Partner, Distributions Paid, Per Unit Distribution Made to Limited Partner, Distributions Declared, Per Unit Distribution Made to Limited Partner, Distributions Declared, Per Unit Distribution Made to Limited Partner, Distribution Date Distribution Made to Limited Partner, Distribution Date Distribution Made to Limited Partner, Date of Record Distribution Made to Limited Partner, Date of Record Risks and Uncertainties [Abstract] Concentration of Credit Risk Concentration Risk Disclosure [Text Block] Quarterly Financial Data [Abstract] Schedule Of Quarterly Financial Data Schedule of Quarterly Financial Information [Table Text Block] Gain On Sale of Assets [Abstract] Gain On Sale of Assets [Abstract] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Gas Stored Base Gas Gas Stored Base Gas [Member] Gas Stored Base Gas [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Gain on Conveyances Gain on Conveyances Amount of gain (loss) on conveyances Gain on Conveyances Cash Received Gain on Conveyances Cash Received Gain on Conveyances Cash Received Deferred Gains On Conveyances Deferred Gains On Conveyances Deferred Gains (Losses) On Conveyances Gain (Loss) on Disposition of Property Plant Equipment Gain (Loss) on Disposition of Property Plant Equipment Supplemental Cash Flow Information [Abstract] Supplemental Cashflow [Table] supplemental cashflow [Table] supplemental cashflow [Table] Supplemental Cash Flow [Line Items] Supplemental Cash Flow [Line Items] Supplemental Cash Flow [Line Items] Capital expenditures included in current liabilities Capital Expenditures Incurred but Not yet Paid Cash paid for interest, net of interest capitalized amounts Interest Paid, Net Cash paid for income taxes Income Taxes Paid Initial Public Offering [Table] Initial Public Offering [Table] Initial Public Offering [Table] Initial Public Offering [Line Items] Initial Public Offering [Line Items] [Line Items] for Initial Public Offering [Table] Noncontrolling Interest, Increase from Subsidiary Equity Issuance Change from net income attributable to the Partnership and transfers to noncontrolling interest Change from net income attributable to the Partnership and transfers to noncontrolling interest Change from net income attributable to the Partnership and transfers to noncontrolling interest Pension and Other Postretirement Benefits Disclosure Pension and Other Postretirement Benefits Disclosure [Text Block] Other Comprehensive (Income) Loss, Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Gain on Sale of Assets Gain on Sale of Assets [Text Block] Gain on Sale of Assets [Text Block] Purchase And Service Obligations [Table] Purchase And Service Obligations [Table] Purchase And Service Obligations [Table] Purchase And Service Obligations [Axis] Purchase And Service Obligations [Axis] Purchase And Service Obligations [Axis] Purchase And Service Obligations [Domain] Purchase And Service Obligations [Domain] Purchase And Service Obligations [Domain] Pipeline Service Agreements [Member] Pipeline Service Agreements [Member] Pipeline Service Agreements [Member] Other Commitments And Contingencies [Line Items] Other Commitments And Contingencies [Line Items] Other Commitments And Contingencies [Line Items] 2016 Purchase And Service Obligations Minimum Fixed Payments Due Current Purchase and service obligations minimum fixed payments due current 2017 Purchase And Service Obligations Minimum Fixed Payments Due In Two Years Purchase and service obligations minimum fixed payments due in two years 2018 Purchase And Service Obligations Minimum Fixed Payments Due In Three Years Purchase and service obligations minimum fixed payments due in three years 2019 Purchase And Service Obligations Minimum Fixed Payments Due In Four Years Purchase and service obligations minimum fixed payments due in four years 2020 Purchase And Service Obligations Minimum Fixed Payments Due In Five Years Purchase and service obligations minimum fixed payments due in five years After Purchase And Service Obligations Minimum Fixed Payments Due Thereafter Purchase and service obligations minimum fixed payments due thereafter Total future minimum payments Purchase And Service Obligations Minimum Fixed Payments Due Purchase and service obligations minimum fixed payments due Property, Plant and Equipment [Abstract] Property, Plant And Equipment Property, Plant and Equipment Disclosure [Text Block] Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Columbia OpCo Columbia OpCo [Member] Columbia OpCo [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Notes Due 2020 Notes Due 2020 [Member] Notes Due 2020 [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Money Pool Money Pool [Member] Money Pool [Member] Revolving Credit Facility Revolving Credit Facility [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Transportation and Storage Services Transportation and Storage Services [Member] Transportation and Storage Services [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Interest Expense, Long-term Debt Interest Expense, Long-term Debt Allowance for Funds Used During Construction, Capitalized Interest Allowance for Funds Used During Construction, Capitalized Interest Short-term Debt, Weighted Average Interest Rate Short-term Debt, Weighted Average Interest Rate Interest Expense, Short-term Borrowings Interest Expense, Short-term Borrowings Accounts Receivable Accounts Receivable, Related Parties, Current Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Default Provision Floor Default Provision Floor Default Provision Floor Short-term borrowings-affiliated Short Term Borrowings Related Parties The amount for short term borrowings (written promise to pay), due to related parties. Debt Instrument, Basis Spread on Variable Rate Debt Instrument, Basis Spread on Variable Rate Debt Instrument, Maturity Date Debt Instrument, Maturity Date Distribution to Parent Distribution to Parent Distribution to Parent Reimbursement of Preformation Capital Reimbursement of Preformation Capital Reimbursement of Preformation Capital Statement of Cash Flows [Abstract] Adjustments to Reconcile Net Income to Net Cash from Operating Activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Deferred income taxes and investment tax credits Deferred Income Taxes and Tax Credits Deferred revenue Recognition of Deferred Revenue Equity-based compensation expense and profit sharing contribution Share-based Compensation Gain on sale of assets and impairment, net Equity earnings in unconsolidated affiliates Income from Unconsolidated Affiliates Income from unconsolidated affiliates. Amortization of debt related costs Amortization of Financing Costs AFUDC equity Public Utilities, Allowance for Funds Used During Construction, Additions Distributions of earnings received from equity investees Proceeds from Equity Method Investment, Dividends or Distributions Accounts receivable Increase (Decrease) in Accounts Receivable Accounts receivable-affiliated Increase (Decrease) in Accounts Receivable, Related Parties Accounts payable Increase (Decrease) in Accounts Payable Accounts payable-affiliated Increase (Decrease) in Accounts Payable, Related Parties Customer deposits Increase (Decrease) in Customer Deposits Taxes accrued Increase (Decrease) in Property and Other Taxes Payable Exchange gas receivable/payable Increase Decrease In Exchange Gas Receivable Payable Increase or decrease in exchange gas receivable payable. Other accruals Increase Decrease In Other Accruals Increase decrease in other accruals. Prepayments and other current assets Increase Decrease In Prepayments And Other Current Assets Increase decrease in prepayments and other current assets. Regulatory assets/liabilities Increase (Decrease) in Regulatory Assets and Liabilities Postretirement and postemployment benefits Increase (Decrease) in Employee Related Liabilities Deferred charges and other noncurrent assets Increase Decrease In Deferred Charges And Other Non Current Assets Increase decrease in deferred charges and other non current assets. Other noncurrent liabilities Increase (Decrease) in Other Operating Liabilities Net Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities Investing Activities Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Insurance recoveries Proceeds from Insurance Settlement, Investing Activities Changes in short-term lendings-affiliated Proceeds from Collection of (Payments to Fund) Short-term Loans to Related Parties Proceeds from Collection of (Payments to Fund) Short-term Loans to Related Parties Proceeds from disposition of assets Proceeds from Sale of Productive Assets Contributions to equity investees Payments to Acquire Equity Method Investments Distributions from equity investees Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital Other investing activities Payments for (Proceeds from) Other Investing Activities Net Cash Flows used for Investing Activities Net Cash Provided by (Used in) Investing Activities Financing Activities Net Cash Provided by (Used in) Financing Activities [Abstract] Change in short-term borrowings-affiliated Proceeds from (Repayments of) Short-term Debt Change in short-term borrowings-affiliated Proceeds from (Repayments of) Short-term Debt to Related Parties Proceeds from (Repayments of) Short-term Debt to Related Parties Issuance of long-term debt-affiliated Proceeds from Issuance of Long-term Debt Payments of long-term debt-affiliated, including current portion Repayments of Long-term Debt Proceeds from issuance of common units, net of offering costs Proceeds from Issuance Initial Public Offering Distribution of IPO proceeds to parent Payments of Capital Distribution Contribution of capital from parent Proceeds from Contributions from Affiliates Distribution to parent Payments of Dividends Quarterly distributions to unitholders Payments of Distributions to Unitholders Payments of Distributions to Unitholders Distribution to noncontrolling interest in Columbia OpCo Payments to Noncontrolling Interests Net Cash Flows from Financing Activities Net Cash Provided by (Used in) Financing Activities Change in cash and cash equivalents Change in cash and cash equivalents from continuing operations Change in cash and cash equivalents from continuing operations. Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at beginning of period Variable Interest Entities And Equity Method Investments Variable Interest Entities And Equity Investments [Text Block] Variable Interest Entities and Equity Investments. Schedule Of Property, Plant And Equipment Property, Plant and Equipment [Table Text Block] Schedule of Depreciation Rates Schedule of Depreciation Rates [Table Text Block] Schedule of Depreciation Rates Segment Reporting [Abstract] Segments Of Business Segment Reporting Disclosure [Text Block] Number of Reportable Segments Number of Reportable Segments Schedule of Trading Securities and Other Trading Assets, Major Types of Trading Securities and Assets [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Trading Securities and Assets [Domain] Major Types of Debt and Equity Securities [Domain] Equity Securities [Member] Equity Securities [Member] Fixed Income Securities [Member] Fixed Income Securities [Member] Commingled Funds [Member] Commingled Funds [Member] Commingled Funds [Member] Private Equity Limited Partnerships [Member] Private Equity Limited Partnerships [Member] Private Equity Limited Partnerships [Member] Real Estate [Member] Real Estate [Member] Mutual Funds [Member] Mutual Funds [Member] Mutual Funds [Member] Cash [Member] Cash [Member] U.S. Equities [Member] United States Equities [Member] United States Equities [Member] Government [Member] US Treasury and Government [Member] Corporate [Member] Corporate Segment [Member] Mortgages/Asset Backed Securities [Member] Mortgages Asset Backed Securities [Member] Mortgages Asset Backed Securities [Member] Short-Term Money Markets [Member] Short Term Money Markets [Member] Short Term Money Markets [Member] U.S. Multi-Strategy [Member] United States Multi Strategy [Member] United States Multi Strategy [Member] International Multi-Strategy [Member] International Multi Strategy [Member] International Multi Strategy [Member] Distressed Opportunities [Member] Distressed Opportunities [Member] Distressed Opportunities [Member] Other Fixed Income [Member] Other Fixed Income [Member] Other Fixed Income [Member] Due To Brokers Net [Member] Due To Brokers Net [Member] Due To Brokers Net [Member] Accrued Investment Income Dividends [Member] Accrued Investment Income Dividends [Member] Accrued Investment Income Dividends [Member] Receivables/Payables [Member] Receivables And Payables [Member] Receivables And Payables [Member] Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) [Member] Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (Level 3) [Member] Fair Value, Inputs, Level 3 [Member] Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items Goodwill and Intangible Assets Disclosure [Abstract] Goodwill And Other Intangible Assets [Table] Goodwill And Other Intangible Assets [Table] Goodwill and other intangible assets Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Columbia Gas Transmission Columbia Gas Transmission [Member] Columbia Gas Transmission. Goodwill And Other Intangible Assets [Line Items] Goodwill And Other Intangible Assets [Line Items] Goodwill and other intangible assets Goodwill Goodwill Fair Value Inputs, Discount Rate Fair Value Inputs, Discount Rate Fair value amount above carrying value of goodwill Reporting Unit, Amount of Fair Value in Excess of Carrying Amount Goodwill, Impairment Loss Goodwill, Impairment Loss Columbia Energy Group Columbia Energy Group [Member] Columbia Energy Group Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] Over-Allotment Option [Member] Over-Allotment Option [Member] Shares Issued, Price Per Share Shares Issued, Price Per Share Partners' Capital Account, Units, Sold in Public Offering Partners' Capital Account, Units, Sold in Public Offering Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest Payments of Stock Issuance Costs Payments of Stock Issuance Costs Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Schedule of Related Party Transactions, Long-Term Debt [Table] Schedule of Related Party Transactions, Long-Term Debt [Table] Schedule of Related Party Transactions, Long-Term Debt [Table] Notes Due 2015 Notes Due 2015 [Member] Notes Due 2015 [Member] Notes Due 2016 Notes Due 2016 [Member] Notes Due 2016 Notes Due 2025 Notes Due 2025 [Member] Notes Due 2025 Notes Due 2032 Notes Due 2032 [Member] Notes Due 2032 [Member] Notes Due 2037 Notes Due 2037 [Member] Notes Due 2037 Notes Due 2037 [1] Notes Due 2037 [1] [Member] Notes Due 2037 [1] Notes Due 2042 Notes Due 2042 [Member] Notes Due 2042 [Member] Notes Due 2042 [1] Notes Due 2042 [1] [Member] Notes Due 2042 Schedule of Related Party Transactions, Long-Term Debt [Line Items] Schedule of Related Party Transactions, Long-Term Debt [Line Items] [Line Items] for Schedule of Related Party Transactions, Long-Term Debt [Table] Debt Instrument, Issuance Date Debt Instrument, Issuance Date Long-term Debt Long-term Debt Short-Term Investments [Member] Short-term Investments [Member] Equities, Minimum Defined Benefit Plan, Target Plan Asset Allocations Range Minimum Equities, Maximum Defined Benefit Plan, Target Plan Asset Allocations Range Maximum Company Structure And Principles Of Consolidation Consolidation, Policy [Policy Text Block] Use Of Estimates Use of Estimates, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Allowance for Uncollectible Accounts Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] Basis Of Accounting For Rate-Regulated Subsidiaries Basis Of Accounting For Rate Regulated Subsidiaries [Policy Text Block] Basis of accounting for rate regulated subsidiaries [Policy Text Block] Property, Plant and Equipment and Related AFUDC and Maintenance Property, Plant and Equipment, Planned Major Maintenance Activities, Policy [Policy Text Block] Gas-Stored Base Gas Gas-Stored Base Gas [Policy Text Block] Gas-Stored Base Gas Accounting Policy Amortization Of Software Costs Amortization Of Software Costs [Policy Text Block] Amortization of software costs [Policy Text Block] Goodwill Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Impairments Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Revenue Recognition Revenue Recognition Accounting Policy, Gross and Net Revenue Disclosure [Policy Text Block] Estimated Rate Refunds Estimated Rate Refunds [Policy Text Block] Estimated Rate Refunds [Policy Text Block] Accounting For Exchange And Balancing Arrangements Of Natural Gas Accounting For Exchange And Balancing Arrangements Of Natural Gas [Policy Text Block] Accounting for exchange and balancing arrangements of natural gas [Policy Text Block] Income Taxes And Investment Tax Credits Income Tax, Policy [Policy Text Block] Environmental Expenditures Environmental Costs, Policy [Policy Text Block] Accounting for Investments Equity Method Investments, Policy [Policy Text Block] Natural Gas and Oil Properties Oil and Gas Properties Policy [Policy Text Block] Document And Entity Information [Abstract] Document And Entity Information. Document Information [Table] Document Information [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Document Information, Document [Axis] Document Information, Document [Axis] Document [Domain] Document [Domain] Document Information [Line Items] Document Information [Line Items] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] Investment, Name [Axis] Investment, Name [Axis] Equity Method Investee, Name [Domain] Investment, Name [Domain] Millennium Pipeline Millennium Pipeline [Member] Millennium Pipeline Company, L.L.C. Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Utilities Operating Expense, Maintenance and Operations Utilities Operating Expense, Maintenance and Operations Schedule of AFUDC Debt and Equity Rates Schedule of AFUDC Debt and Equity Rates [Table Text Block] Schedule of AFUDC Debt and Equity Rates Capitalized Exploratory Well Costs, Roll Forward Capitalized Exploratory Well Costs, Roll Forward [Table Text Block] Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Asset Retirement Obligation [Abstract] Changes In Liability For Asset Retirement Obligations Schedule of Change in Asset Retirement Obligation [Table Text Block] Other, Net Other Income and Other Expense Disclosure [Text Block] Schedule of Regulatory Matters by Gas Distribution and Operations [Table] Schedule of Regulatory Matters by Gas Distribution and Operations [Table] Schedule of regulatory matters by gas distribution and operations. Regulatory Matters [Line Items] Regulatory Matters [Line Items] Regulatory Matters [Line Items] Regulatory asset not earning return on investment Deferred Gas Cost Regulatory Asset Not Earning Return On Investment Deferred gas cost regulatory asset not earning return on investment Expenses recovered as components of cost of service and regulatory orders Expenses Recovered As Components Of Cost Of Service And Regulatory Orders Expenses recovered as components of cost of service and regulatory orders Remaining life for the costs to be recovered, years Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided Customer Refund Customer Refund Customer Refund Initial Customer Refund Initial Customer Refund Initial Customer Refund Annual base rate reduction effective January 1, 2014 Annual base rate reduction effective January 1, 2014 Annual base rate reduction effective January 1, 2014 Capital Cost Recovery Mechanism Revenue Requirement Capital Cost Recovery Mechanism Revenue Requirement Capital Cost Recovery Mechanism Revenue Requirement Required Annual Capital Maintenance Expenditure Required Annual Capital Maintenance Expenditure Required Annual Capital Maintenance Expenditure Annual Capital Cost Recovery Mechanism Limit Annual Capital Cost Recovery Mechanism Limit Annual Capital Cost Recovery Mechanism Limit Annual Capital Cost Recovery Mechanism Limit Tolerance Annual Capital Cost Recovery Mechanism Limit Tolerance Annual Capital Cost Recovery Mechanism Limit Tolerance Total Capital Cost Recovery Mechanism Over Five-year Term Total Capital Cost Recovery Mechanism Over Five-year Term Total Capital Cost Recovery Mechanism Over Five-year Term Depreciation Rate Reduction Depreciation Rate Reduction Depreciation Rate Reduction Expected Modernization Investment Expected Modernization Investment Expected Modernization Investment LLC Membership Limited Liability Company [Member] Limited Partnership Hardy Storage Company, L.L.C. Hardy Storage [Member] Hardy Storage Company, LLC [Member] Pennant Midstream, L.L.C. Pennant [Member] Pennant Midstream, L.L.C. [Member] Millennium Pipeline Company, L.L.C Percentage of voting power held Business Acquisition, Percentage of Voting Interests Acquired Pipeline and Other Transmission Assets Pipeline and Other Transmission Assets [Member] Pipeline and Other Transmission Assets [Member] Storage Facilities Storage Facilities [Member] Storage Facilities [Member] Gas Gathering and Processing Equipment Gas Gathering and Processing Equipment [Member] Construction Work In Process Construction Work In Process [Member] Construction work in process General Plant, Software, and Other Assets General Plant, Software, and Other Assets [Member] General Plant, Software, and Other Assets [Member] Property Plant and Equipment Property, Plant and Equipment, Gross Accumulated Depreciation and Amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Net Property, Plant and Equipment Property, Plant and Equipment, Net Transactions With Affiliates Related Party Transactions Disclosure [Text Block] Income Tax Disclosure [Abstract] Schedule Of Components Of Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule Of Reasons Behind Differences In Computation Of Total Income Taxes Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule Of Principal Components Of Net Deferred Tax Liability Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Statement of Financial Position [Abstract] Assets Assets [Abstract] Current Assets Assets, Current [Abstract] Cash and cash equivalents Accounts receivable (less reserve of $0.3 and $0.3, respectively) Accounts Receivable, Net, Current Accounts Receivable-affiliated Materials and supplies, at average cost Inventory, Raw Materials and Supplies, Gross Exchange gas receivable Exchange gas receivable Exchange gas receivable. Deferred Property Taxes Deferred Property Taxes Deferred property taxes Deferred income taxes Deferred Tax Assets, Net, Current Prepayments and other Other Assets, Current Total Current Assets Assets, Current Investments Regulated Entity, Other Assets, Noncurrent [Abstract] Unconsolidated affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Other investments Other Long-term Investments Total Investments Investments and Other Noncurrent Assets Property, Plant and Equipment Public Utilities, Property, Plant and Equipment [Abstract] Property, plant and equipment Public Utilities, Property, Plant and Equipment, Plant in Service Accumulated depreciation and amortization Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Net Property, Plant and Equipment Public Utilities, Property, Plant and Equipment, Net Other Noncurrent Assets Assets, Noncurrent [Abstract] Regulatory assets Regulatory Assets, Noncurrent Goodwill Postretirement and postemployment benefits assets Deferred charges and other Deferred charges and other Deferred charges and other Total Other Noncurrent Assets Other Assets, Noncurrent Total Assets Assets Liabilities and Equity Liabilities and Equity [Abstract] Current Liabilities Liabilities, Current [Abstract] Current portion of long-term debt-affiliated Long-term Debt and Capital Lease Obligations, Current Short-term borrowings Short-term Debt Accounts payable Accounts Payable, Current Accounts payable-affiliated Accounts Payable, Related Parties, Current Customer deposits Customer Deposits, Current Taxes accrued Taxes Payable, Current Exchange gas payable Exchange gas payable Exchange gas payable Deferred revenue Deferred Revenue, Current Accrued capital expenditures Accrued Capital Expenditures Accrued Capital Expenditures Accrued compensation and related costs Employee-related Liabilities, Current Other accruals Other Liabilities, Current Total Current Liabilities Liabilities, Current Noncurrent Liabilities Liabilities, Noncurrent [Abstract] Long-term debt-affiliated Long-term Debt and Capital Lease Obligations Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Accrued liability for postretirement and postemployment benefits Pension and Other Postretirement and Postemployment Benefit Plans, Liabilities, Noncurrent Regulatory liabilities Regulatory Liability, Noncurrent Asset retirement obligations Asset Retirement Obligations, Noncurrent Other noncurrent liabilities Other Liabilities, Noncurrent Total Noncurrent Liabilities Liabilities, Noncurrent Total Liabilities Liabilities Equity and Partners' Capital Partners' Capital [Abstract] Net parent investment Other Partners' Capital Limited Partners' Capital Account Limited Partners' Capital Account Accumulated other comprehensive loss Total Columbia Pipeline Partners LP partners' equity and capital Partners' Capital Noncontrolling Interest in Columbia OpCo Partners' Capital Attributable to Noncontrolling Interest Total Equity and Partners' Capital Total Liabilities and Equity and Partners' Capital Liabilities and Equity Schedule of Guarantor Obligations Schedule of Guarantor Obligations [Table Text Block] Future Minimum Lease Payments Required Under Operating And Capital Leases Schedule Of Future Minimum Lease Payments Required Under Operating And Capital Leases [Table Text Block] Schedule Of Future Minimum Lease Payments Required Under Operating And Capital Leases Estimated Aggregate Amounts Of Minimum Fixed Payments On Purchase And Service Obligations Estimated Aggregate Amounts Of Minimum Fixed Payments On Purchase And Service Obligations [Table Text Block] Estimated Aggregate Amounts Of Minimum Fixed Payments On Purchase And Service Obligations Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Guarantor Obligations by Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Guarantee of Indebtedness of Others Guarantee of Indebtedness of Others [Member] Letters Of Credit Letter of Credit [Member] 2016 Guarantee Obligations Maximum Exposure Year One Guarantee obligations maximum exposure year one. 2017 Guarantee Obligations Maximum Exposure Year Two Guarantee obligations maximum exposure year two. 2018 Guarantee Obligations Maximum Exposure Year Three Guarantee obligations maximum exposure year three. 2019 Guarantee Obligations Maximum Exposure Year Four Guarantee obligations maximum exposure year four. 2020 Guarantee Obligations Maximum Exposure Year Five Guarantee obligations maximum exposure year five. After Guarantee Obligations Maximum Exposure Thereafter Guarantee obligations maximum exposure thereafter. Total Guarantor Obligations, Maximum Exposure, Undiscounted Fair Value Fair Value Disclosures [Text Block] Short-term Debt [Abstract] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Test Period [Axis] Test Period [Axis] Test Period [Axis] Test Period [Domain] Test Period [Domain] [Domain] for Test Period [Axis] Period 1 Period 1 [Member] Period 1 [Member] Period 2 Period 2 [Member] Period 2 [Member] Period 3 Period 3 [Member] Period 3 [Member] Acquisition Period Acquisition Period [Member] Acquisition Period [Member] Maximum Maximum [Member] Federal Funds Effective Swap Rate [Member] Federal Funds Effective Swap Rate [Member] Eurodollar [Member] Eurodollar [Member] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Credit Facilities [Member] Credit Facilities [Member] Credit Facilities [Member] Commercial Paper Commercial Paper [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Margin Rate Margin Rate Margin Rate Line of Credit Facility, Commitment Fee Percentage Line of Credit Facility, Commitment Fee Percentage Ratio of Indebtedness to Net Capital Ratio of Indebtedness to Net Capital Line of Credit Facility, Amount Outstanding Long-term Line of Credit Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Income Statement [Abstract] Operating Revenues Gross Profit [Abstract] Transportation revenues Natural Gas Midstream Revenue Transportation revenues-affiliated Natural Gas Midstream Revenue Related Party Midstream refers to those gas industry activities that fall between exploration and production (upstream) and refining and marketing (downstream). It may be applied to the gathering, processing, transmission and storage of natural gas; including the treating of natural gas to remove impurities, along with the sale of by-products such as residue gas, natural gas liquids and condensate with a related party. Storage revenues Natural Gas Storage Revenue Storage revenues-affiliated Natural Gas Storage Revenue Related Parties Revenue from storage facilities, such as a LNG ( Liquefied Natural Gas) storage facility. Other revenues Other Revenue, Net Total Operating Revenues Revenues Operating Expenses Operating Expenses [Abstract] Operation and maintenance Operating and maintenance-affiliated Utilities Operating Expense, Maintenance and Operations Related Parties Amount of operating expense for routine plant maintenance, repairs and operations of regulated operation. Gain (Loss) on Disposition of Assets Gain (Loss) on Disposition of Assets Property and other taxes Taxes, Miscellaneous Total Operating Expenses Operating Expenses Equity Earnings in Unconsolidated Affiliates Income (Loss) from Equity Method Investments Operating Income Operating Income (Loss) Other Income (Deductions) Interest expense Interest Expense Interest expense-affiliated Interest Expense, Related Party Other, net Other Nonoperating Income (Expense) Total Other Income (Deductions), net Nonoperating Income (Expense) Income before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income Taxes Income Tax Expense (Benefit) Net Income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Income (Loss), Including Portion Attributable to Noncontrolling Interest Less: Net income attributable to noncontrolling interest in Columbia OpCo subsequent to IPO Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to controlling interest subsequent to IPO Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax [Abstract] Weighted average limited partner units outstanding (basic and diluted) Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Quarterly Financial Data [Table] Quarterly Financial Data [Table] Quarterly Financial Data [Table] Quarterly Financial Data [Line Items] Quarterly Financial Data [Line Items] Quarterly Financial Data [Line Items] Operating Revenues Revenue, Net Operating Income Net Income Net income attributable to noncontrolling interest in Columbia OpCo subsequent to IPO Net income attributable to limited partners subsequent to the IPO Schedule Of Short-Term Borrowings Schedule of Short-term Debt [Table Text Block] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Current Portion of Long Term Debt-affiliated, Fair Value Current Portion of Long Term Debt, Fair Value The fair value amount of the current portion of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. Long-term debt-affiliated, Fair Value Long-term Debt, Fair Value Nature of Operations And Summary of Significant Accounting Policies [Abstract] Nature of Operations And Summary of Significant Accounting Policies [Abstract] Significant Accounting Policies Significant Accounting Policies [Text Block] Discount Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Expected Long-Term Rate of Return on Plan Assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets Rate of Compensation Increases Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Partners' Equity And Cash Distribution Partners' Equity And Cash Distribution [Text Block] Disclosure of the composition of Partners' equity and cash distributions Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Credit Concentration Risk [Member] Credit Concentration Risk [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Revenues Concentration Risk, Percentage Concentration Risk, Percentage Schedule of Cash Flow, Supplemental Disclosures Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Postretirement Health Coverage Postretirement Health Coverage [Member] 2016 Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months 2017 Defined Benefit Plan, Expected Future Benefit Payments, Year Two 2018 Defined Benefit Plan, Expected Future Benefit Payments, Year Three 2019 Defined Benefit Plan, Expected Future Benefit Payments, Year Four 2020 Defined Benefit Plan, Expected Future Benefit Payments, Year Five 2021-2025 Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter Service Cost Expected return on assets Defined Benefit Plan, Expected Return on Plan Assets Amortization of prior service cost Recognized actuarial loss Net Periodic Benefit Costs Defined Benefit Plan Net Periodic Benefit Costs Defined Benefit Plan Net Periodic Benefit Cost Settlement loss Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements Total Net Periodic Benefits Cost Defined Benefit Plan, Net Periodic Benefit Cost Distribution Made to Limited Partner, Cash Distributions Paid Distribution Made to Limited Partner, Cash Distributions Paid Total gains or losses (unrealized / realized) Defined Benefit Plan, Actual Return on Plan Assets Still Held Purchases Defined Benefit Plan Purchases Defined Benefit Plan Purchases (Sales) Defined Benefit Plan, Sales Defined Benefit Plan, Sales Transfers into/(out of) level 3 Defined Benefit Plan, Transfers Between Measurement Levels Defined Benefit Plan, Separation Allocation Defined Benefit Plan, Separation Allocation Defined Benefit Plan, Separation Allocation Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Schedule of Income Tax Expense Benefit [Table] Schedule of Income Tax Expense Benefit [Table] Schedule of Income Tax Expense Benefit [Table] Schedule of Income Tax Expense/Benefit [Line Items] Schedule of Income Tax Expense Benefit [Line Items] [Line Items] for Schedule of Income Tax Expense Benefit [Table] Current Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Total Current Current Income Tax Expense (Benefit) Deferred Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Total Deferred Deferred Income Tax Expense (Benefit) Deferred Investment Credits Deferred Other Tax Expense (Benefit) Total Income Taxes Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Statutory federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Unrecognized tax benefits Unrecognized Tax Benefits Columbia Pipeline Group Columbia Pipeline Group [Member] Columbia Pipeline Group Guarantees Line of Credit Facility, Maximum Borrowing Capacity Commercial Paper Commercial Paper Credit facilities borrowings Line of Credit Facility Used For Credit Support for Subsidiaries Line of Credit Facility Used For Credit Support for Subsidiaries Line of Credit Facility Used For Credit Support for Subsidiaries Line of Credit Facility Used For Corporate Purposes Line of Credit Facility Used For Corporate Purposes Line of Credit Facility Used For Corporate Purposes Ozone Level Maximum Ozone Level Maximum Ozone Level Maximum Percentage Reduction in Methane Emissions Percentage Reduction in Methane Emissions Percentage Reduction in Methane Emissions Hours of Operation Hours of Operation Hours of Operation Operating lease payments Operating Leases, Rent Expense, Net Replacement Years Replacement Years Replacement Years Changes in Company's Liability for Asset Retirement Obligations [Table] Changes in Company's Liability for Asset Retirement Obligations [Table] Changes in Company's Liability for Asset Retirement Obligations [Table] Asset Retirement Obligation [Axis] Asset Retirement Obligation [Axis] Asset Retirement Obligation [Axis] Beginning Balance Noncontributed net parent investment adjustments Noncontributed net parent investment adjustments Noncontributed net parent investment adjustments Accretion expense Asset Retirement Obligation, Accretion Expense Additions Asset Retirement Obligation, Liabilities Incurred Settlements Asset Retirement Obligation, Liabilities Settled Change in estimated cash flows Asset Retirement Obligation, Revision of Estimate Ending Balance Net Income Per Limited Partner Unit Earnings Per Share [Text Block] Schedule of AFUDC Debt and Equity Rates [Table] Schedule of AFUDC Debt and Equity Rates [Table] Schedule of AFUDC Debt and Equity Rates [Table] Rate Type Rate Type [Axis] Rate Type [Axis] Rate Type [Domain] Rate Type [Domain] [Domain] for Rate Type [Axis] Debt Rate Debt Rate [Member] Debt Rate Equity Rate Equity Rate [Member] Equity Rate Columbia Gulf Columbia Gulf [Member] Columbia Gulf Schedule of AFUDC Debt and Equity Rates [Line Items] Schedule of AFUDC Debt and Equity Rates [Line Items] [Line Items] for Schedule of AFUDC Debt and Equity Rates [Table] Public Utilities, Allowance for Funds Used During Construction, Rate Public Utilities, Allowance for Funds Used During Construction, Rate Schedule of Net Income Per Limited Partner Unit Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Subsequent Event [Table] Subsequent Event [Table] Columbia Pipeline Partners LP Columbia Pipeline Partners LP [Member] Columbia Pipeline Partners LP [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Effective Income Tax Rate Reconciliation, Amount [Abstract] Schedule of Reasons Behind Differences in Computation of Total Income Taxes [Table] Schedule of Reasons Behind Differences in Computation of Total Income Taxes [Table] Schedule of Reasons Behind Differences in Computation of Total Income Taxes [Table] Reasons Behind Differences in Computation of Total Income Taxes [Axis] Reasons Behind Differences in Computation of Total Income Taxes [Axis] Reasons Behind Differences in Computation of Total Income Taxes [Axis] Reasons Behind Differences in Computation of Total Income Taxes [Domain] Reasons Behind Differences in Computation of Total Income Taxes [Domain] [Domain] for Reasons Behind Differences in Computation of Total Income Taxes [Axis] Schedule of Reasons Behind Differences in Computation of Total Income Taxes [Line Items] Schedule of Reasons Behind Differences in Computation of Total Income Taxes [Line Items] [Line Items] for Schedule of Reasons Behind Differences in Computation of Total Income Taxes [Table] Book income before income taxes Tax expense at statutory federal income tax rate, value Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Tax expense at statutory federal income tax rate, rate State income taxes, net of federal income tax benefit, value Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount State income taxes, net of federal income tax benefit, rate Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Income not subject to income tax at the partnership level, rate Effective Income Tax Reconciliation, Income Not Subject to Income Tax At The Partnership Level Amount Effective Income Tax Reconciliation, Income Not Subject to Income Tax At The Partnership Level, Amount Income not subject to income tax at the partnership level, value Effective Income Tax Reconciliation, Income Not Subject to Income Tax At The Partnership Level Effective Income Tax Reconciliation, Income Not Subject to Income Tax At The Partnership Level AFUDC-Equity, value Regulatory Treatment Of AFUDC Equity Regulatory Treatment Of AFUDC Equity AFUDC-Equity, rate Regulatory Treatment Of Afduc Equity Regulatory Treatment Of AFDUC Equity Other, net, value Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Other net, rate Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Total Income Taxes, rate Income Taxes Income Tax Disclosure [Text Block] Initial Public Offering Stockholders' Equity Note Disclosure [Text Block] Property, Plant and Equipment [Table] Gas Gathering and Processing Facilities Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service Accounts receivable less reserve Allowance for Doubtful Accounts Receivable, Current Limited Partners' Capital Account, Units Issued Limited Partners' Capital Account, Units Issued Limited Partners' Capital Account, Units Outstanding Limited Partners' Capital Account, Units Outstanding Schedule Of Other, Net [Table] Schedule Of Other, Net [Table] Schedule Of Other, Net [Table] Schedule Of Other, Net [Line Items] Schedule Of Other, Net [Line Items] [Line Items] for Schedule Of Other, Net [Table] AFUDC Equity Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Miscellaneous Miscellaneous Nonoperating Income (Expense) Miscellaneous Nonoperating Income (Expense) Total Other, net Concentration Risk, Benchmark Description Concentration Risk, Benchmark Description Basis Of Accounting Presentation [Table] Basis Of Accounting Presentation [Table] Basis Of Accounting Presentation [Table] Order [Axis] Order [Axis] Order [Axis] Order [Domain] Order [Domain] [Domain] for Order [Axis] Previous [Member] Previous [Member] Previous [Member] Hardy Storage Pennant Segments [Axis] Segments [Axis] Reporting Segment [Domain] Segments [Domain] Joint Ventures [Member] Corporate Joint Venture [Member] Basis Of Accounting Presentation [Line Items] Basis Of Accounting Presentation [Line Items] Basis Of Accounting Presentation [Line Items] Pipeline Length Pipeline Length Pipeline Length Equity Method Investment, Initial Ownership Percentage Equity Method Investment, Initial Ownership Percentage Equity Method Investment, Initial Ownership Percentage Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Cash Received from Buy-In Cash Received from Buy-In Cash Received from Buy-In Gain on Buy-In Gain on Buy-In Gain on Buy-In Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest Base Gas Purchases Base Gas Purchases Base Gas Purchases Amortized software costs Capitalized Computer Software, Amortization Unamortized software costs Capitalized Computer Software, Gross Asset Impairment Charges Gain (Loss) on Sale of Assets and Asset Impairment Charges Royalty Revenue Royalty Revenue Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects Schedule of Transactions With Affiliates Schedule of Related Party Transactions [Table Text Block] Schedule of Related Party Transactions, Long-Term Debt Schedule of Related Party Transactions, Long-Term Debt [Table Text Block] [Table Text Block] for Schedule of Related Party Transactions, Long-Term Debt [Table] Asset Retirement Obligations Asset Retirement Obligation Disclosure [Text Block] Quarterly Financial Data Quarterly Financial Information [Text Block] Scenario, Forecast Scenario, Forecast [Member] Regulatory Liability [Axis] Regulatory Liability [Axis] Regulatory Liability [Domain] Regulatory Liability [Domain] Defined Benefit Plan, Fair Value of Plan Assets Defined Benefit Plan, Actuarial Gain (Loss) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Decrease In Net Periodic Benefit Cost Change In Net Periodic Benefit Cost Change In Net Periodic Benefit Cost Defined Benefit Plan, Net Periodic Benefit Cost Expected contribution Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year Percentage of investments Percentage Of Investments Percentage of investments Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Increase in funded status other postretirement benefit plans Increase In Funded Status Other Postretirement Benefit Plans Increase in funded status other postretirement benefit plans Funded status of plan Amortization of transition obligation Defined Benefit Plan, Amortization of Transition Obligations (Assets) Regulatory assets Regulatory liabilities Regulatory Liabilities Expected return on plan assets Change in Net Periodic Benefit Cost due to Interim Measurement Change in Net Periodic Benefit Cost due to Interim Measurement Change in Net Periodic Benefit Cost due to Interim Measurement - associated with August 31, 2012 pension plan settlement Schedules of Concentration of Risk, by Risk Factor Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Schedule of Regulatory Liabilities [Table] Schedule of Regulatory Liabilities [Table] Cost Of Removal Cost Of Removal [Member] Cost Of Removal [Member] Regulatory Effects Of Accounting For Income Taxes Regulatory Effects Of Accounting For Income Taxes [Member] Regulatory Effects Of Accounting For Income Taxes [Member] Other Liabilities Other Liabilities [Member] Regulatory Liabilities [Line Items] Regulatory Liabilities [Line Items] Total Regulatory Liabilities 2016 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2017 Operating Leases, Future Minimum Payments, Due in Two Years 2018 Operating Leases, Future Minimum Payments, Due in Three Years 2019 Operating Leases, Future Minimum Payments, Due in Four Years 2020 Operating Leases, Future Minimum Payments, Due in Five Years After Operating Leases, Future Minimum Payments, Due Thereafter Total future minimum payments Operating Leases, Future Minimum Payments Due Goodwill Goodwill and Intangible Assets Disclosure [Text Block] Regulatory Matters Public Utilities Disclosure [Text Block] Schedule Of Allocation of Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Schedule Of Fair Value and Changes In The Fair Value Of The Plan Assets Schedule Of Fair Value And Changes In Fair Value Of Pension Plan Assets [Table Text Block] Schedule Of Fair Value and Changes in Fair Value Of Pension Plan Assets [Table Text Block] Schedule Of Reconciliation Of The Plan Funded Status Schedule of Net Funded Status [Table Text Block] Schedule Of Significant Actuarial Assumptions In Determining Funded Status Plan Schedule of Assumptions Used [Table Text Block] Schedule Of One-Percentage-Point Change In Assumed Health Care Cost Trend Rates Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block] Schedule Of Expected Payments To Participants In Pension Plan Schedule of Expected Benefit Payments [Table Text Block] Components Of The Plans' Net Periodic Benefits Cost Schedule of Net Benefit Costs [Table Text Block] Schedule Of Key Assumptions That Were Used To Calculate The Net Periodic Benefits Cost Schedule Of Assumptions Used To Calculate The Net Periodic Benefits Cost [Table Text Block] Schedule Of Assumptions Used To Calculate The Net Periodic Benefits Cost Schedule Of Changes In Plan Assets And Projected Benefit Obligations Recognized In Other Comprehensive Income Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Transportation revenues Storage revenues Other revenues Related Party Transaction, Other Revenues from Transactions with Related Party Operation and maintenance expense Interest expense Interest Income Interest Income, Related Party Current portion of long-term debt Short-term borrowings Accounts Payable Long-term Debt Net Revenues Equity Method Investment, Summarized Financial Information, Revenue Operating Income Equity Method Investment, Summarized Financial Information, Income (Loss) from Continuing Operations before Extraordinary Items Net Income Equity Method Investment, Summarized Financial Information, Net Income (Loss) Current Assets Equity Method Investment, Summarized Financial Information, Assets Noncurrent Assets Equity Method Investment, Summarized Financial Information, Noncurrent Assets Current Liabilities Equity Method Investment, Summarized Financial Information, Current Liabilities Noncurrent Liabilities Equity Method Investment, Summarized Financial Information, Liabilities Total Members’ Equity Equity Method Investment Summarized Financial Information, Equity Partners' Capital Account, Distributions Partners' Capital Account, Return of Capital Partners' Capital Account, Return of Capital Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Notes Due 2027 [Member] Notes Due 2027 [Member] Notes Due 2027 [Member] Number of interest rate swap agreements Number of Interest Rate Derivatives Held Notional amount of interest rate swap agreements Derivative, Notional Amount Number of counterparties entered into interest rate swap agreement Number Of Counterparties Entered Into Interest Rate Swap Agreement Number of counterparties entered into interest rate swap agreement. Number Of Notes Tranches Through Private Placement Issuance Number Of Notes Tranches Through Private Placement Issuance Number of notes tranches through private placement issuance. Refinancing of long-term debt Debt Instrument, Face Amount Debt Instrument, Maturity Date Other Comprehensive Income Unrecognized Gain Loss On Derivatives Arising During Period Net Of Tax Other Comprehensive Income Unrecognized Gain Loss On Derivatives Arising During Period Net Of Tax Other Comprehensive Income Unrecognized Gain Loss On Derivatives Arising During Period Net Of Tax Unrealized loss, amortization period Unrealized Gain Loss On Derivatives, Amortization Period Unrealized Gain Loss On Derivatives, Amortization Period Equity Method Investment, Percent Not Contributed to Partnership Equity Method Investment, Percent Not Contributed to Partnership Equity Method Investment, Percent Not Contributed to Partnership Short-Term Borrowings Short-term Debt [Text Block] Accumulated Other Comprehensive Loss Comprehensive Income (Loss) Note [Text Block] Distributions Made to Limited Partner [Table] Distributions Made to Limited Partner [Table] Common and Subordinated Common and Subordinated [Member] Common and Subordinated [Member] First First [Member] First [Member] Second Second [Member] Second [Member] Third Third [Member] Third [Member] Final Final [Member] Final [Member] Distribution Made to Limited Partner [Line Items] Distribution Made to Limited Partner [Line Items] Subordination Period End Percentage Subordination Period End Percentage Subordination Period End Percentage Minimum Quarterly Distribution, Per Unit Distribution to Limited Partner, Minimum Quarterly Distribution, Per Unit Distribution to Limited Partner, Minimum Quarterly Distribution, Per Unit Pro Rata Percentage of Distribution in Excess of Minimum Percent Of Excess Distribution Percentage of distribution over minimum distributed, pro rata Schedule of Principal Components of Net Deferred Tax Liability [Table] Schedule of Principal Components of Net Tax Expense [Table] [Table] Schedule of Principal Components of Net Tax Expense [Table] Schedule of Principal Components of Net Deferred Tax Liability [Line Items] Schedule of Principal Components of Net Tax Expense [Table] [Line Items] [Line Items] for Schedule of Principal Components of Net Tax Expense [Table] Accelerated depreciation and other property differences Accelerated Depreciation And Other Property Differences Accelerated depreciation and other property differences Pension and other postretirement/postemployment benefits Deferred Tax Liability, Pension and Other Postretirement Benefits Deferred Tax Liability, Pension and Other Postretirement/Postemployment Benefits Other regulatory assets Deferred Tax Liabilities, Regulatory Assets Other, net Deferred Tax Liabilities, Other Total Deferred Tax Liabilities Deferred Tax Liabilities, Gross Deferred investment tax credits and other regulatory liabilities Deferred Investment Tax Credits And Other Regulatory Liabilities Deferred Investment Tax Credits And Other Regulatory Liabilities Net operating loss carryforward and AMT credit carryforward Deferred Tax Assets, Operating Loss Carryforwards Other accrued liabilities Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities Total Deferred Tax Assets Deferred Tax Assets, Gross Deferred Tax Liabilities, Net Deferred Tax Liabilities, Net Less: Deferred income taxes related to current assets and liabilities Non-Current Deferred Tax Liability Discount Rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Rate of Compensation Increases Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Trend for Next Year Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year Ultimate Trend Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Year Ultimate Trend Reached Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate