Statements Of Consolidated and Combined Cash Flows - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Operating Activities    
Net Income $ 239.0  
Adjustments to Reconcile Net Income to Net Cash from Operating Activities:    
Depreciation and amortization 65.3  
Deferred income taxes and investment tax credits 10.5  
Deferred revenue (0.1)  
Equity-based compensation expense and 401(k) profit sharing contribution 3.6  
Gain on sale of assets (13.6)  
Income from unconsolidated affiliates (28.9)  
Amortization of Financing Costs 0.2  
AFUDC equity (8.4)  
Distributions of earnings received from equity investees 27.9  
Changes in Assets and Liabilities:    
Accounts receivable 13.9  
Accounts receivable-affiliated 17.1  
Accounts payable 1.0  
Accounts payable-affiliated (14.7)  
Customer deposits 1.0  
Taxes accrued (10.2)  
Exchange gas receivable/payable 0.3  
Other accruals (4.5)  
Prepayments and other current assets 17.0  
Regulatory assets/liabilities 25.5  
Postretirement and postemployment benefits (13.5)  
Deferred charges and other noncurrent assets (1.9)  
Other noncurrent liabilities (1.6)  
Net Cash Flows from Operating Activities 324.9  
Investing Activities    
Capital expenditures (430.6)  
Insurance recoveries 2.1  
Change in short-term lendings-affiliated (527.1)  
Proceeds from disposition of assets 19.0  
Distributions from (contributions to) equity investees 2.2  
Other investing activities (13.4)  
Net Cash Flows used for Investing Activities (947.8)  
Financing Activities    
Change in short-term borrowings 20.0  
Change in short-term borrowings-affiliated (180.2)  
Issuance of long-term debt-affiliated 0.0  
Payments of long-term debt-affiliated, including current portion (957.8)  
Proceeds from the issuance of common units, net of offering costs 1,168.4  
Distribution of IPO proceeds to parent (500.0)  
Contribution of capital from parent 1,217.3  
Partners' Capital Account, Distributions (9.2)  
Net Cash Flows from Financing Activities 758.5  
Change in cash and cash equivalents 135.6  
Cash and cash equivalents at beginning of period 0.5  
Cash and Cash Equivalents at End of Period 136.1  
Predecessor [Member]    
Operating Activities    
Net Income   $ 151.5
Adjustments to Reconcile Net Income to Net Cash from Operating Activities:    
Depreciation and amortization   58.5
Deferred income taxes and investment tax credits   47.4
Deferred revenue   2.0
Equity-based compensation expense and 401(k) profit sharing contribution   1.7
Gain on sale of assets   (17.8)
Income from unconsolidated affiliates   (20.9)
Amortization of Financing Costs   0.0
AFUDC equity   (4.3)
Distributions of earnings received from equity investees   12.9
Changes in Assets and Liabilities:    
Accounts receivable   (25.2)
Accounts receivable-affiliated   19.0
Accounts payable   24.2
Accounts payable-affiliated   (17.7)
Customer deposits   75.2
Taxes accrued   (11.1)
Exchange gas receivable/payable   4.7
Other accruals   4.3
Prepayments and other current assets   20.4
Regulatory assets/liabilities   25.6
Postretirement and postemployment benefits   (8.9)
Deferred charges and other noncurrent assets   (3.2)
Other noncurrent liabilities   (0.8)
Net Cash Flows from Operating Activities   337.5
Investing Activities    
Capital expenditures   (296.6)
Insurance recoveries   6.8
Change in short-term lendings-affiliated   (10.4)
Proceeds from disposition of assets   4.9
Distributions from (contributions to) equity investees   (54.8)
Other investing activities   (3.4)
Net Cash Flows used for Investing Activities   (353.5)
Financing Activities    
Change in short-term borrowings   0.0
Change in short-term borrowings-affiliated   (312.6)
Issuance of long-term debt-affiliated   328.4
Payments of long-term debt-affiliated, including current portion   0.0
Proceeds from the issuance of common units, net of offering costs   0.0
Distribution of IPO proceeds to parent   0.0
Contribution of capital from parent   0.0
Partners' Capital Account, Distributions   0.0
Net Cash Flows from Financing Activities   15.8
Change in cash and cash equivalents   (0.2)
Cash and cash equivalents at beginning of period $ 0.5 0.3
Cash and Cash Equivalents at End of Period   $ 0.1