Income Taxes - Book Income Reconciliaiton To Income Tax Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Expected income tax provision (benefit) based on federal statutory rate (1)	$ 1.0	$ 5.6	$ (159.4)
State income tax provision (benefit), net of federal benefit	0.1	0.4	(11.4)
Statutory rate change	0.0	(210.6)	0.0
Income tax provision (benefit) from ENLK	(2.1)	0.9	1.2
Unit-based compensation	0.7	2.9	0.0
Non-deductible expense related to asset impairment	10.7	0.0	173.8
Other	7.8	4.0	0.4
Total income tax provision (benefit)	$ 18.2	(196.8)	$ 4.6
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)