Asset Retirement Obligations (Changes In Company's Liability For Asset Retirement Obligations) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Beginning Balance $ 23.2    
Noncontributed net parent investment adjustments (0.4) [1]    
Accretion expense 0.3    
Additions 0    
Settlements 0    
Change in estimated cash flows 0    
Ending Balance 23.1    
Predecessor [Member]      
Beginning Balance   26.3 23.2
Noncontributed net parent investment adjustments   0 [1]  
Accretion expense   0.4  
Additions   0  
Settlements   0  
Change in estimated cash flows   0  
Ending Balance   $ 26.7 $ 23.2
[1] Reflects the removal of amounts related to Crossroads Pipeline Company, which was included in the Predecessor but was not contributed to the Partnership.