Transactions With Affiliates (Schedule of Affiliated Transactions) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Related Party Transaction [Line Items] | |||
| Transportation revenues | $ 47.1 | ||
| Storage revenues | 26.2 | ||
| Other revenues | 0.2 | ||
| Operation and maintenance expense | 164.1 | ||
| Interest expense | 26.8 | ||
| Interest Income | 4.8 | ||
| Accounts Receivable | 149.4 | ||
| Current portion of long-term debt | 0.0 | ||
| Short-term borrowings | 42.1 | ||
| Accounts Payable | 86.3 | ||
| Long-term Debt | $ 630.9 | ||
| Predecessor | |||
| Related Party Transaction [Line Items] | |||
| Transportation revenues | $ 95.8 | $ 94.3 | |
| Storage revenues | 53.2 | 53.6 | |
| Other revenues | 0.3 | 0.3 | |
| Operation and maintenance expense | 122.9 | 118.1 | |
| Interest expense | 62.0 | 37.9 | |
| Interest Income | 0.5 | $ 0.5 | |
| 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 | ||