Members' Equity - Computation and Distribution Activity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
EnLink Midstream, LLC interest in net income (loss)													$ 212.8	$ (460.0)	$ (357.0)
Distributed earnings allocated to:
Total distributed earnings													187.3	185.5	166.1
Undistributed income (loss) allocated to:
Total undistributed loss													25.5	(645.5)	(523.1)
Net income (loss) allocated to:
Total net income (loss)													$ 212.8	$ (460.0)	$ (357.0)
Basic and diluted net income (loss) per unit:
Basic (in dollars per share)	$ 1.12	$ 0.03	$ 0.03	$ (0.01)	$ (0.02)	$ 0.00	$ 0.01	$ (2.56)	$ (1.18)	$ (1.18)	$ 0.09	$ 0.10	$ 1.18	$ (2.56)	$ (2.17)
Diluted (in dollars per share)	1.11	0.03	0.03	(0.01)	(0.02)	0.00	0.01	(2.56)	(1.18)	(1.18)	0.09	0.10	$ 1.17	$ (2.56)	$ (2.17)
Distribution declared/unit (in dollars per share)	$ 0.259	$ 0.255	$ 0.255	$ 0.255	$ 0.255	$ 0.255	$ 0.255	$ 0.255	$ 0.255	$ 0.255	$ 0.250	$ 0.245
Unvested restricted units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
EnLink Midstream, LLC interest in net income (loss)													$ 2.8	$ (5.4)	$ (2.5)
Distributed earnings allocated to:
Total distributed earnings													2.5	2.2	1.1
Undistributed income (loss) allocated to:
Total undistributed loss													0.3	(7.5)	(3.6)
Net income (loss) allocated to:
Total net income (loss)													2.8	(5.4)	(2.5)
Common Unit
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
EnLink Midstream, LLC interest in net income (loss)													210.0	(454.6)	(354.5)
Distributed earnings allocated to:
Total distributed earnings													184.8	183.3	165.0
Undistributed income (loss) allocated to:
Total undistributed loss													25.2	(638.0)	(519.5)
Net income (loss) allocated to:
Total net income (loss)													$ 210.0	$ (454.6)	$ (354.5)