Goodwill and Intangible Assets - Amortization Expense (Details) - EnLink Midstream Partners, LP $ in Millions	Dec. 31, 2018 USD ($)
Finite-Lived Intangible Assets [Line Items]
2019	$ 123.7
2020	123.7
2021	123.7
2022	123.7
2023	123.6
Thereafter	755.2
Total	$ 1,373.6