Statements Of Consolidated and Combined Operations (USD $)
In Millions, except Per Share data, unless otherwise specified
 2 Months Ended 3 Months Ended
Mar. 31, 2015
Mar. 31, 2015
Mar. 31, 2014
Operating Revenues      
Transportation revenues   $ 247.9  
Transportation revenues-affiliated   28.7  
Storage revenues   36.6  
Storage revenues-affiliated   13.3  
Other revenues   12.7  
Total Operating Revenues   339.2  
Operating Expenses      
Operation and maintenance   110.0  
Operation and maintenance-affiliated   36.1  
Depreciation and amortization   32.3  
Gain on sale of assets   (5.3)  
Property and other taxes   19.0  
Total Operating Expenses   192.1  
Equity Earnings in Unconsolidated Affiliates   14.9  
Operating Income   162.0  
Other Income (Deductions)      
Interest expense-affiliated   (11.4)  
Other, net   4.3  
Total Other Deductions, net   (7.1)  
Income before Income Taxes   154.9  
Income Taxes   23.7  
Net Income 88.5 131.2  
Income (Loss) Attributable to Noncontrolling Interest 75.2    
Net Income (Loss) Allocated to Limited Partners 13.3    
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 $ 0.13    
Weighted average limited partner units outstanding (basic and diluted)      
Weighted Average Number of Shares Outstanding, Basic and Diluted 100.6    
Predecessor [Member]      
Operating Revenues      
Transportation revenues     246.9
Transportation revenues-affiliated     28.6
Storage revenues     36.3
Storage revenues-affiliated     13.7
Other revenues     20.0
Total Operating Revenues     345.5
Operating Expenses      
Operation and maintenance     137.8
Operation and maintenance-affiliated     28.3
Depreciation and amortization     29.7
Gain on sale of assets     (17.5)
Property and other taxes     18.5
Total Operating Expenses     196.8
Equity Earnings in Unconsolidated Affiliates     9.8
Operating Income     158.5
Other Income (Deductions)      
Interest expense-affiliated     (12.1)
Other, net     1.8
Total Other Deductions, net     (10.3)
Income before Income Taxes     148.2
Income Taxes     55.7
Net Income     92.5
Common Units [Member]      
Other Income (Deductions)      
Net Income (Loss) Allocated to Limited Partners 7.1    
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 $ 0.13    
Weighted average limited partner units outstanding (basic and diluted)      
Weighted Average Number of Shares Outstanding, Basic and Diluted 53.8    
Subordinated Units [Member]      
Other Income (Deductions)      
Net Income (Loss) Allocated to Limited Partners $ 6.2    
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 $ 0.13    
Weighted average limited partner units outstanding (basic and diluted)      
Weighted Average Number of Shares Outstanding, Basic and Diluted 46.8