Statements Of Consolidated and Combined Operations - USD ($)
shares in Millions, $ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Operating Revenues        
Transportation revenues $ 265.8   $ 751.0  
Transportation revenues-affiliated 0.0   47.1  
Storage revenues 49.5   122.3  
Storage revenues-affiliated 0.0   26.2  
Other revenues 4.7   28.2  
Total Operating Revenues 320.0   974.8  
Operating Expenses        
Operation and maintenance 144.9   392.9  
Operation and maintenance-affiliated 37.4   112.1  
Depreciation and amortization 33.4   98.7  
Gain on sale of assets and impairment, net (38.4)   (52.0)  
Property and other taxes 15.2   53.3  
Total Operating Expenses 192.5   605.0  
Equity Earnings in Unconsolidated Affiliates 15.3   44.2  
Operating Income 142.8   414.0  
Other Income (Deductions)        
Interest expense (1.2)   (1.2)  
Interest expense-affiliated (6.4)   (24.1)  
Other, net 9.4   18.6  
Total Other Income (Deductions), net 1.8   (6.7)  
Income before Income Taxes 144.6   407.3  
Income Taxes 0.0   23.7  
Net Income 144.6   383.6  
Income (Loss) Attributable to Noncontrolling Interest 122.6   289.3  
Net Income (Loss) Allocated to Limited Partners $ 22.0   $ 51.6 [1]  
Net income attributable to partners' ownership interest subsequent to IPO per limited partner unit (basic and diluted)        
Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax $ 0.22   $ 0.51  
Weighted average limited partner units outstanding (basic and diluted)        
Weighted Average Number of Shares Outstanding, Basic and Diluted 100.6   100.6  
Predecessor        
Operating Revenues        
Transportation revenues   $ 236.1   $ 743.5
Transportation revenues-affiliated   18.8   66.3
Storage revenues   35.9   108.2
Storage revenues-affiliated   13.2   40.1
Other revenues   13.6   48.4
Total Operating Revenues   317.6   1,006.5
Operating Expenses        
Operation and maintenance   163.2   477.1
Operation and maintenance-affiliated   31.8   89.6
Depreciation and amortization   29.2   87.7
Gain on sale of assets and impairment, net   (3.0)   (20.8)
Property and other taxes   14.6   50.3
Total Operating Expenses   235.8   683.9
Equity Earnings in Unconsolidated Affiliates   12.0   32.9
Operating Income   93.8   355.5
Other Income (Deductions)        
Interest expense   0.0   0.0
Interest expense-affiliated   (14.4)   (39.1)
Other, net   3.6   8.0
Total Other Income (Deductions), net   (10.8)   (31.1)
Income before Income Taxes   83.0   324.4
Income Taxes   29.8   119.7
Net Income   $ 53.2   $ 204.7
Common Units [Member]        
Other Income (Deductions)        
Net Income (Loss) Allocated to Limited Partners $ 11.8   $ 27.9  
Net income attributable to partners' ownership interest subsequent to IPO per limited partner unit (basic and diluted)        
Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax $ 0.22   $ 0.52  
Weighted average limited partner units outstanding (basic and diluted)        
Weighted Average Number of Shares Outstanding, Basic and Diluted 53.8   53.8  
Subordinated Units [Member]        
Other Income (Deductions)        
Net Income (Loss) Allocated to Limited Partners $ 10.2   $ 23.7  
Net income attributable to partners' ownership interest subsequent to IPO per limited partner unit (basic and diluted)        
Net Income (Loss), Per Outstanding Limited Partnership and General Partnership Unit, Basic and Diluted, Net of Tax $ 0.22   $ 0.51  
Weighted average limited partner units outstanding (basic and diluted)        
Weighted Average Number of Shares Outstanding, Basic and Diluted 46.8   46.8  
[1] Net income attributable to limited partners and in excess of distribution is for the period subsequent to the IPO.