Investments - Equity Investments (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Equity investments without readily determinable fair values	$ 291	$ 326	$ 337	$ 136	$ 137	$ 137
Equity investments under the equity method of accounting	7		7
Total equity investments	$ 298		$ 344