Income Taxes (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended		12 Months Ended
	Jul. 18, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax [Line Items]
U.S. statutory income tax rate		21.00%		35.00%	21.00%	35.00%
Income tax benefits in conjunction with favorable tax settlements		$ 14
Foreign earnings repatriated			$ 92
Current income tax expense		(27)		$ 12	$ (23)	$ 32
Valuation allowance against U.S. deferred tax assets, percent					100.00%		100.00%
Gain recognized		(23)		$ 22	$ (11)	$ 30
U.S. [Member]
Income Tax [Line Items]
Change in deferred tax valuation allowance					$ 129
Canada [Member]
Income Tax [Line Items]
Change in deferred tax valuation allowance		$ (74)
EnLink and General Partner [Member] | Subsequent Event [Member]
Income Tax [Line Items]
Gain recognized	$ 2,500
Repatriated Earnings [Member]
Income Tax [Line Items]
Current income tax expense			$ 0