Investments - Carrying Value of Equity Investments Without Readily Determinable Fair Values (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity Securities without Readily Determinable Fair Value [Roll Forward]
Carrying value, beginning of period	$ 261	$ 105	$ 307	$ 107
Additions	0	160	0	160
Downward adjustments for observable price changes and impairment	0	0	(40)	0
Foreign currency translation and other	3	(3)	(3)	(5)
Carrying value, end of period	264	$ 262	264	$ 262
Cumulative downward adjustments for price changes and impairment	$ 121		$ 121