Investments - Equity Investments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Investments [Abstract]
Equity investments without readily determinable fair values	$ 264	$ 261	$ 307	$ 262	$ 105	$ 107
Equity investments under the equity method of accounting	8		7
Total equity investments	$ 272		$ 314