Consolidations and Transfers of Financial Assets - Transfers of Financial Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Transfers of Financial Assets [Line Items]
Portfolio securitizations: unpaid principal balance	$ 35,300	$ 56,100	$ 100,500	$ 235,900
Unconsolidated VIEs
Transfers of Financial Assets [Line Items]
Retained interests: principal and interest received	72	$ 86	220	$ 308
Unconsolidated VIEs | Single Class MBS, REMIC & Megas
Transfers of Financial Assets [Line Items]
Retained interests: unpaid principal balance	844		844		$ 910
Retained interests: fair value	$ 1,300		$ 1,300		$ 1,400