Derivative Financial Instruments - Dealer Counterparties and Central Clearing Parties (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Credit Derivatives [Line Items]
Unsecured positions in a net gain with counterparties after collateral postings	$ 1,088	$ 951
Asset Pledged as Collateral
Credit Derivatives [Line Items]
Securities, fair value	40,105	41,270
Dealer and other counterparties:
Credit Derivatives [Line Items]
Cash and other collateral received from counterparties	664	609
Derivatives in a net gain position	685	735
Unsecured positions in a net gain with counterparties after collateral postings	80	126
Cash collateral posted	1,045	960
Derivatives in a net loss position	1,155	1,052
Central counterparties clearing:
Credit Derivatives [Line Items]
Derivatives in a net gain position	7	2
Cash collateral posted	8	14
Derivatives in a net loss position	0	8
Central counterparties clearing: | Asset Pledged as Collateral
Credit Derivatives [Line Items]
Securities, fair value	$ 1,058	$ 1,249