Investments - Carrying Value of Equity Investments Without Readily Determinable Fair Values (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Investments [Abstract]
Cumulative upward adjustments for observable price changes	$ 280		$ 280
Cumulative downward adjustments for price changes and impairment	121		121
Equity Securities without Readily Determinable Fair Value [Roll Forward]
Carrying value, beginning of period	528	$ 296	539	$ 307
Additions	1	0	1	0
Upward adjustments for observable price changes	41	0	41	0
Downward adjustments for observable price changes and impairment	0	(40)	0	(40)
Foreign currency translation and other	1	5	(10)	(6)
Carrying value, end of period	$ 571	$ 261	$ 571	$ 261