Transactions With Affiliates (Schedule of Affiliated Transactions) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2014
Related Party Transaction [Line Items]      
Transportation revenues-affiliated $ 28.7    
Storage revenues 13.3    
Other revenues 0.1    
Operation and maintenance-affiliated 36.1    
Interest expense 11.4    
Interest income 1.0    
Accounts receivable 833.7    
Long-term Debt and Capital Lease Obligations, Current 0    
Short-term Debt 7.0    
Accounts payable 41.0    
Long-term debt 630.9    
Predecessor [Member]      
Related Party Transaction [Line Items]      
Transportation revenues-affiliated   28.6  
Storage revenues   13.7  
Other revenues   0.1  
Operation and maintenance-affiliated   28.3  
Interest expense   12.1  
Interest income   0.1  
Accounts receivable     153.8
Long-term Debt and Capital Lease Obligations, Current     115.9
Short-term Debt     247.3
Accounts payable     49.9
Long-term debt     $ 1,472.8