Investments - Equity Security Investments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Cost
Equity securities with readily determinable fair values	$ 180
Equity securities with no readily determinable fair value	225
Hybrid equity securities	58
Total	463
Equity securities with readily determinable fair values		$ 61
Equity securities with no readily determinable fair value		183
Hybrid equity securities		58
Total		302
Carrying Value
Equity securities with readily determinable fair values	202
Equity securities with no readily determinable fair value	255
Hybrid equity securities	44
Total	$ 501
Equity securities with readily determinable fair values		64
Equity securities with no readily determinable fair value		192
Hybrid equity securities		47
Total		$ 303