Fair Values - Fund Interests Measured Based on Net Asset Value (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Measured Based on Net Asset Value
Carrying Value	$ 4,747	$ 3,829
Commitment	865	780
Private equity
Measured Based on Net Asset Value
Carrying Value	2,492	2,367
Commitment	615	644
Carrying Value of Nonredeemable Funds by Contractual Maturity
Less than 5 years	982
5-10 years	1,163
Over 10 years	347
Total	2,492
Real estate
Measured Based on Net Asset Value
Carrying Value	2,064	1,403
Commitment	248	136
Carrying Value of Nonredeemable Funds by Contractual Maturity
Less than 5 years	403
5-10 years	1,283
Over 10 years	378
Total	2,064
Hedge
Measured Based on Net Asset Value
Carrying Value	191	59
Commitment	$ 2	$ 0