Commitments and Contingencies - Pledged Assets and Funds in Trust (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
AFS securities	$ 24,307	$ 15,366
Debt Securities, Trading, Restricted	163	55
Equity securities	77	38
Investment funds	193	103
Derivative assets pledged as collateral	88	65
Other investments	286	170
Restricted cash	1,218	628
Total restricted assets	37,202	25,394
Other Commitments [Line Items]
Short-term investments	68	120
Asset Pledged as Collateral
Commitments and Contingencies Disclosure [Abstract]
Mortgage loans, net of allowances	10,802	8,849
Other Commitments [Line Items]
Mortgage loans, net of allowances	$ 10,802	$ 8,849