Other Information (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Other Current Assets:
Natural gas and NGLs inventory	$ 22.0	$ 30.1
Prepaid expenses and other	11.6	11.1
Natural gas and NGLs inventory, prepaid expenses, and other	33.6	41.2
Other Current Liabilities:
Accrued interest	64.2	35.6
Accrued wages and benefits, including taxes	14.5	30.4
Accrued ad valorem taxes	13.2	27.8
Capital expenditure accruals	47.4	48.8
Onerous performance obligations	15.0	15.2
Other	67.5	65.1
Other current liabilities	$ 221.8	$ 222.9