Transactions With Affiliates (Narrative) (Details) - USD ($)
$ in Millions |
3 Months Ended |
|
|
Mar. 31, 2016 |
Mar. 31, 2015 |
Dec. 31, 2015 |
Dec. 05, 2014 |
| Related Party Transaction [Line Items] |
|
|
|
|
| Interest Expense, Long-term Debt |
$ 7.7
|
$ 12.2
|
|
|
| Allowance for Funds Used During Construction, Capitalized Interest |
0.7
|
1.0
|
|
|
| Interest Expense, Short-term Borrowings |
0.2
|
$ 0.2
|
|
|
| Accounts receivable |
122.6
|
|
$ 149.4
|
|
| Line of Credit Facility, Maximum Borrowing Capacity |
2,600.0
|
|
|
|
| Default Provision Floor |
50.0
|
|
|
|
| Short-term borrowings-affiliated |
348.8
|
|
42.1
|
|
| Distribution to Parent |
108.9
|
|
|
|
| Short-term Debt |
15.0
|
|
15.0
|
|
| Transportation and Storage Services |
|
|
|
|
| Related Party Transaction [Line Items] |
|
|
|
|
| Accounts receivable |
$ 7.0
|
|
8.9
|
|
| Money Pool |
|
|
|
|
| Related Party Transaction [Line Items] |
|
|
|
|
| Short-term Debt, Weighted Average Interest Rate |
0.54%
|
1.07%
|
|
|
| Accounts receivable |
$ 115.6
|
|
$ 140.5
|
|
| Line of Credit Facility, Maximum Borrowing Capacity |
750.0
|
|
|
|
| Revolving Credit Facility |
|
|
|
|
| Related Party Transaction [Line Items] |
|
|
|
|
| Line of Credit Facility, Maximum Borrowing Capacity |
500.0
|
|
|
$ 1,500.0
|
| Notes Due 2020 |
|
|
|
|
| Related Party Transaction [Line Items] |
|
|
|
|
| Line of Credit Facility, Maximum Borrowing Capacity |
$ 2,300.0
|
|
|
|
| Debt Instrument, Interest Rate, Stated Percentage |
4.70%
|
|
|
|
| Debt Instrument, Maturity Date |
Dec. 31, 2020
|
|
|
|
| Columbia OpCo |
|
|
|
|
| Related Party Transaction [Line Items] |
|
|
|
|
| Reimbursement of Preformation Capital |
|
$ 500.0
|
|
|