Income Taxes - Narrative and Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Issuance of common units for ENLK public common units related to the Merger	$ 399,000,000.0
Unrecognized tax benefits	0	$ 0
Domestic Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards	1,600,000,000
Deferred tax assets, operating loss carryforwards, domestic	341,400,000
State and Local Jurisdiction
Income Taxes [Line Items]
Operating loss carryforwards	816,200,000
Deferred tax assets, operating loss carryforwards, domestic	$ 44,800,000