Statements Of Consolidated and Combined Operations - USD ($)
shares in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Operating Revenues      
Transportation revenues $ 1,052.2    
Transportation revenues-affiliated 47.1    
Storage revenues 171.4    
Storage revenues-affiliated 26.2    
Other revenues 34.9    
Total Operating Revenues 1,331.8    
Operating Expenses      
Operation and maintenance 526.1    
Operating and maintenance-affiliated 164.1    
Depreciation and amortization 135.0    
Gain (Loss) on Disposition of Assets (54.7)    
Property and other taxes 71.2    
Total Operating Expenses 841.7    
Equity Earnings in Unconsolidated Affiliates 60.2    
Operating Income 550.3    
Other Income (Deductions)      
Interest expense (1.4)    
Interest expense-affiliated (26.8)    
Other, net 32.0    
Total Other Income (Deductions), net 3.8    
Income before Income Taxes 554.1    
Income Taxes 23.9    
Net Income 530.2    
Income (Loss), Including Portion Attributable to Noncontrolling Interest 530.2    
Less: Net income attributable to noncontrolling interest in Columbia OpCo subsequent to IPO 413.5    
Net income attributable to controlling interest subsequent to IPO $ 74.0    
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 $ 0.74    
Weighted average limited partner units outstanding (basic and diluted)      
Weighted Average Number of Shares Outstanding, Basic and Diluted 100.6    
Predecessor      
Operating Revenues      
Transportation revenues   $ 990.9 $ 850.9
Transportation revenues-affiliated   95.8 94.3
Storage revenues   144.0 142.8
Storage revenues-affiliated   53.2 53.6
Other revenues   63.0 37.8
Total Operating Revenues   1,346.9 1,179.4
Operating Expenses      
Operation and maintenance   630.7 507.1
Operating and maintenance-affiliated   122.9 118.1
Depreciation and amortization   118.6 106.9
Gain (Loss) on Disposition of Assets   (34.5) (18.6)
Property and other taxes   67.1 62.2
Total Operating Expenses   904.8 775.7
Equity Earnings in Unconsolidated Affiliates   46.6 35.9
Operating Income   488.7 439.6
Other Income (Deductions)      
Interest expense   0.0 0.0
Interest expense-affiliated   (62.0) (37.9)
Other, net   8.8 17.6
Total Other Income (Deductions), net   (53.2) (20.3)
Income before Income Taxes   435.5 419.3
Income Taxes   166.4 152.4
Net Income   269.1 266.9
Income (Loss), Including Portion Attributable to Noncontrolling Interest   $ 269.1 $ 266.9
Common Units      
Other Income (Deductions)      
Net income attributable to controlling interest subsequent to IPO $ 39.6    
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 $ 0.74    
Weighted average limited partner units outstanding (basic and diluted)      
Weighted Average Number of Shares Outstanding, Basic and Diluted 53.8    
Subordinated Units      
Other Income (Deductions)      
Net income attributable to controlling interest subsequent to IPO $ 33.8    
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 $ 0.72    
Weighted average limited partner units outstanding (basic and diluted)      
Weighted Average Number of Shares Outstanding, Basic and Diluted 46.8