Transactions With Affiliates (Schedule of Affiliated Transactions) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2015 |
Sep. 30, 2014 |
Sep. 30, 2015 |
Sep. 30, 2014 |
Dec. 31, 2014 |
|
| Related Party Transaction [Line Items] | |||||
| Transportation revenues | $ 0.0 | $ 47.1 | |||
| Storage revenues | 0.0 | 26.2 | |||
| Other revenues | 0.0 | 0.2 | |||
| Operation and maintenance | 37.4 | 112.1 | |||
| Interest expense | 6.4 | 24.1 | |||
| Interest income | 0.9 | 4.2 | |||
| Accounts receivable | 394.1 | 394.1 | |||
| Current portion of long-term debt | 0.0 | 0.0 | |||
| Short-term borrowings | 2.4 | 2.4 | |||
| Accounts payable | 35.8 | 35.8 | |||
| Long-term debt | $ 630.9 | $ 630.9 | |||
| Predecessor | |||||
| Related Party Transaction [Line Items] | |||||
| Transportation revenues | $ 18.8 | $ 66.3 | |||
| Storage revenues | 13.2 | 40.1 | |||
| Other revenues | 0.0 | 0.2 | |||
| Operation and maintenance | 31.8 | 89.6 | |||
| Interest expense | 14.4 | 39.1 | |||
| Interest income | $ 0.1 | $ 0.3 | |||
| Accounts receivable | $ 153.8 | ||||
| Current portion of long-term debt | 115.9 | ||||
| Short-term borrowings | 247.3 | ||||
| Accounts payable | 49.9 | ||||
| Long-term debt | $ 1,472.8 | ||||