Fair Value Measurements - Effect of Interest Rate Swap Contracts (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Total interest expense which reflects the effects of cash flow hedges	$ (131)	$ (146)	$ (379)	$ (447)
Hedged item	(5)	(5)	(15)	(15)
Derivative designated as hedging instrument	1	5	5	15
Earnings (loss) from equity investments	$ 2	$ 4	$ (3)	$ 17