Statements of Consolidated and Combined Balance Sheets (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Current Assets    
Cash and cash equivalents $ 7.2 $ 0.5
Accounts receivable (less reserve of $0.3 and $0.3, respectively) 125.1  
Accounts receivable-affiliated 833.7  
Materials and supplies, at average cost 25.2  
Exchange gas receivable 28.0  
Regulatory assets 7.7  
Deferred property taxes 47.8  
Deferred income taxes 0  
Prepayments and other 11.6  
Total Current Assets 1,086.3  
Investments and Other Assets    
Unconsolidated affiliates 439.5  
Other investments 5.6  
Total Investments and Other Assets 445.1  
Property, Plant and Equipment    
Property, plant and equipment 8,080.1  
Accumulated depreciation and amortization (2,982.8)  
Net Property, Plant and Equipment 5,097.3  
Other Noncurrent Assets    
Regulatory assets 127.5  
Goodwill 1,975.5  
Postretirement and postemployment benefits assets 113.0  
Deferred charges and other 10.9  
Total Other Noncurrent Assets 2,226.9  
Total Assets 8,855.6  
Current Liabilities    
Current portion of long-term debt 0  
Short-term borrowings-affiliated 7.0  
Accounts payable 43.9  
Accounts payable-affiliated 41.0  
Customer deposits 13.8  
Taxes accrued 89.8  
Exchange gas payable 27.3  
Deferred revenue 22.4  
Regulatory liabilities 9.6  
Legal and environmental 0.2  
Accrued capital expenditures 80.3  
Other accruals 51.9  
Total Current Liabilities 387.2  
Noncurrent Liabilities    
Long-term debt-affiliated 630.9  
Deferred income taxes 1.0  
Accrued liability for postretirement and postemployment benefits 39.1  
Regulatory liabilities 286.7  
Asset retirement obligations 23.1 23.2
Other noncurrent liabilities 84.7  
Total Noncurrent Liabilities 1,065.5  
Liabilities 1,452.7  
Equity and Partners' Capital    
Net parent investment 0  
Accumulated other comprehensive loss (4.2) (16.7)
Total Columbia Pipeline Partners LP partners' equity and capital 1,240.2  
Noncontrolling Interest in Columbia OpCo 6,162.7  
Total Equity and Partners' Capital 7,402.9 4,171.3
Total Liabilities and Equity and Partners' Capital 8,855.6  
Predecessor [Member]    
Current Assets    
Cash and cash equivalents   0.5
Accounts receivable (less reserve of $0.3 and $0.3, respectively)   149.3
Accounts receivable-affiliated   153.8
Materials and supplies, at average cost   24.9
Exchange gas receivable   34.8
Regulatory assets   6.1
Deferred property taxes   48.9
Deferred income taxes   24.6
Prepayments and other   14.8
Total Current Assets   457.7
Investments and Other Assets    
Unconsolidated affiliates   444.3
Other investments   6.2
Total Investments and Other Assets   450.5
Property, Plant and Equipment    
Property, plant and equipment   7,931.6
Accumulated depreciation and amortization   (2,971.4)
Net Property, Plant and Equipment   4,960.2
Other Noncurrent Assets    
Regulatory assets   151.9
Goodwill   1,975.5
Postretirement and postemployment benefits assets   102.7
Deferred charges and other   9.0
Total Other Noncurrent Assets   2,239.1
Total Assets   8,107.5
Current Liabilities    
Current portion of long-term debt   115.9
Short-term borrowings-affiliated   247.3
Accounts payable   56.1
Accounts payable-affiliated   49.9
Customer deposits   13.4
Taxes accrued   106.9
Exchange gas payable   34.7
Deferred revenue   22.2
Regulatory liabilities   1.3
Legal and environmental   1.5
Accrued capital expenditures   61.1
Other accruals   67.4
Total Current Liabilities   777.7
Noncurrent Liabilities    
Long-term debt-affiliated   1,472.8
Deferred income taxes   1,239.0
Accrued liability for postretirement and postemployment benefits   44.7
Regulatory liabilities   294.3
Asset retirement obligations   23.2
Other noncurrent liabilities   84.5
Total Noncurrent Liabilities   3,158.5
Liabilities   3,936.2
Equity and Partners' Capital    
Net parent investment   4,188.0
Accumulated other comprehensive loss   (16.7)
Total Columbia Pipeline Partners LP partners' equity and capital   4,171.3
Noncontrolling Interest in Columbia OpCo   0
Total Equity and Partners' Capital   4,171.3
Total Liabilities and Equity and Partners' Capital   8,107.5
Common Units [Member]    
Equity and Partners' Capital    
Limited Partners' Capital Account 948.4  
Common Units [Member] | Predecessor [Member]    
Equity and Partners' Capital    
Limited Partners' Capital Account   0
Subordinated Units [Member]    
Equity and Partners' Capital    
Limited Partners' Capital Account 296.0  
Subordinated Units [Member] | Predecessor [Member]    
Equity and Partners' Capital    
Limited Partners' Capital Account   $ 0