Investments - Carrying Value of Equity Investments Without Readily Determinable Fair Values (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity Securities without Readily Determinable Fair Value [Roll Forward]
Carrying value, beginning of period	$ 326	$ 137	$ 337	$ 137
Downward adjustments for observable price changes and impairment	(40)	0	(40)	0
Foreign currency translation and other	5	(1)	(6)	(1)
Carrying value, end of period	291	$ 136	291	$ 136
Cumulative downward adjustments for price changes and impairment	$ 121		$ 121