Employee Incentive Plans - Restricted and Performance Awards (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restricted incentive units
Number of Units
Non-vested, beginning of period (in shares)				1,889,310
Granted (in shares)	194,185			1,059,062
Vested (in shares)				(556,262)
Forfeited (in shares)				(138,187)
Non-vested, end of period (in shares)		2,253,923		2,253,923
Aggregate intrinsic value, end of period		$ 37.1		$ 37.1
Weighted Average Grant-Date Fair Value
Non-vested, beginning of period (in dollars per share)				$ 16.33
Granted (in dollars per share)				15.67
Vested (in dollars per share)				24.24
Forfeited (in dollars per share)				12.24
Non-vested, end of period (in dollars per share)		$ 14.32		$ 14.32
Fair value of units vested	$ 3.0	$ 0.4	$ 0.4	$ 13.5	$ 20.8
Units withheld for payroll taxes (in shares)				178,824
Aggregate intrinsic value of units vested		0.4	0.3	$ 9.3	14.6
Unrecognized compensation cost related to non-vested restricted incentive units		$ 19.2		$ 19.2
Unrecognized compensation costs, weighted average period for recognition				1 year 11 months
Vesting period				3 years
Restricted incentive units | EnLink Midstream Partners, LP
Number of Units
Non-vested, beginning of period (in shares)				1,980,224
Granted (in shares)	200,753			1,166,464
Vested (in shares)				(601,581)
Forfeited (in shares)				(148,572)
Non-vested, end of period (in shares)		2,396,535		2,396,535
Aggregate intrinsic value, end of period		$ 37.2		$ 37.2
Weighted Average Grant-Date Fair Value
Non-vested, beginning of period (in dollars per share)				$ 15.81
Granted (in dollars per share)				15.15
Vested (in dollars per share)				22.04
Forfeited (in dollars per share)				12.29
Non-vested, end of period (in dollars per share)		$ 14.14		$ 14.14
Fair value of units vested	$ 3.0	$ 0.5	0.5	$ 13.3	21.0
Units withheld for payroll taxes (in shares)				189,584
Aggregate intrinsic value of units vested		0.4	$ 0.4	$ 9.1	$ 15.7
Unrecognized compensation cost related to non-vested restricted incentive units		$ 20.2		$ 20.2
Unrecognized compensation costs, weighted average period for recognition				1 year 11 months
Vesting period				3 years
Performance units
Number of Units
Non-vested, beginning of period (in shares)				548,839
Granted (in shares)				223,865
Vested (in shares)		0	0	(102,555)	0
Forfeited (in shares)				(70,918)
Non-vested, end of period (in shares)		599,231		599,231
Aggregate intrinsic value, end of period		$ 9.9		$ 9.9
Weighted Average Grant-Date Fair Value
Non-vested, beginning of period (in dollars per share)				$ 22.14
Granted (in dollars per share)				21.63
Vested (in dollars per share)				40.48
Forfeited (in dollars per share)				17.75
Non-vested, end of period (in dollars per share)		$ 19.33		$ 19.33
Fair value of units vested				$ 4.2
Units withheld for payroll taxes (in shares)				28,846
Aggregate intrinsic value of units vested				$ 1.9
Unrecognized compensation cost related to non-vested restricted incentive units		$ 7.5		$ 7.5
Unrecognized compensation costs, weighted average period for recognition				2 years
Vesting period				3 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Beginning TSR Price (in dollars per share)	$ 16.55
Risk-free interest rate	2.38%
Volatility factor	51.36%
Distribution yield	6.70%
Performance units | Minimum
Weighted Average Grant-Date Fair Value
Percent of units vesting				0.00%
Performance units | Maximum
Weighted Average Grant-Date Fair Value
Percent of units vesting				200.00%
Performance units | EnLink Midstream Partners, LP
Number of Units
Non-vested, beginning of period (in shares)				585,285
Granted (in shares)				256,345
Vested (in shares)		0	0	(115,328)	0
Forfeited (in shares)				(76,351)
Non-vested, end of period (in shares)		649,951		649,951
Aggregate intrinsic value, end of period		$ 10.1		$ 10.1
Weighted Average Grant-Date Fair Value
Non-vested, beginning of period (in dollars per share)				$ 20.52
Granted (in dollars per share)				19.24
Vested (in dollars per share)				35.39
Forfeited (in dollars per share)				16.62
Non-vested, end of period (in dollars per share)		$ 17.83		$ 17.83
Fair value of units vested				$ 4.1
Units withheld for payroll taxes (in shares)				34,069
Aggregate intrinsic value of units vested				$ 2.0
Unrecognized compensation cost related to non-vested restricted incentive units		$ 7.4		$ 7.4
Unrecognized compensation costs, weighted average period for recognition				2 years
Vesting period				3 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Beginning TSR Price (in dollars per share)	$ 15.44
Risk-free interest rate	2.38%
Volatility factor	43.85%
Distribution yield	10.50%
Performance units | EnLink Midstream Partners, LP | Minimum
Weighted Average Grant-Date Fair Value
Percent of units vesting				0.00%
Performance units | EnLink Midstream Partners, LP | Maximum
Weighted Average Grant-Date Fair Value
Percent of units vesting				200.00%