Components of Accumulated Other Comprehensive Loss, Net - MEC (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 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	$ 4	$ 7	(20)	$ (28)
Other comprehensive income (loss)	242	(191)	(177)	(134)
Ending balance - Accumulated other comprehensive loss, net	(1,883)		(1,883)
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			(20)	(28)
Other comprehensive income (loss)	242	(191)	(177)	(134)
Ending balance - unrealized gains (losses) on cash flow hedges	(13)	8	(13)	8
Ending balance - Accumulated other comprehensive loss, net	$ (1,883)	$ (2,079)	$ (1,883)	$ (2,079)