Newly-Formed Joint Ventures, Acquisitions and Divestitures - Pro Forma Impact of Permian Acquisition on Consolidated Statement of Operations (Details) - Permian Acquisition [Member] - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Pro forma consolidated results of operations [Abstract]
Revenues	$ 2,131.8	$ 6,126.2
Net income (loss)	$ (154.8)	$ (196.0)