Income Taxes - Book Income Reconciliaiton To Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected income tax provision (benefit) based on federal statutory rate of 35%	$ 5.6	$ (159.4)	$ (116.0)
State income taxes, net of federal benefit	0.4	(11.4)	(8.3)
Statutory rate change	210.6	0.0	0.0
Income tax expense from partnership	0.9	1.2	(0.5)
Unit-based compensation	2.9	0.0	0.0
Non-deductible expense related to asset impairment	0.0	173.8	149.4
Other	4.0	0.4	1.1
Total income tax provision (benefit)	(196.8)	$ 4.6	$ 25.7
ENLC
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Statutory rate change	185.7
EnLink Midstream Partners, LP
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Statutory rate change	$ 24.9