Special Purpose Entities, Including Variable Interest Entities - Summary of Fair Value of Fixed Income Securities, by Asset-Type, Held by Consolidated Variable Interest Entities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Variable Interest Entities [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 2,651
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	147	$ 149
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 8	$ 8