Components of Accumulated Other Comprehensive Loss, Net - MEC (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance - Accumulated other comprehensive loss, net			$ (1,706)
Other comprehensive income (loss), unrealized gains (losses) on cash flow hedges	$ 9	$ (27)	(24)	$ (35)
Other comprehensive income (loss)	128	(58)	(419)	57
Ending balance - Accumulated other comprehensive loss, net	(2,125)		(2,125)
Accumulated Other Comprehensive (Loss) Income, Net [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance - unrealized gains (losses) on cash flow hedges			7	36
Beginning balance - Accumulated other comprehensive loss, net			(1,706)	(1,945)
Other comprehensive income (loss), unrealized gains (losses) on cash flow hedges			(24)	(35)
Other comprehensive income (loss)	128	(58)	(419)	57
Ending balance - unrealized gains (losses) on cash flow hedges	(17)	1	(17)	1
Ending balance - Accumulated other comprehensive loss, net	$ (2,125)	$ (1,888)	$ (2,125)	$ (1,888)