Consolidations and Transfers of Financial Assets - Transfers of Financial Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Transfers of Financial Assets [Line Items]
Portfolio securitizations: unpaid principal balance	$ 102,800	$ 216,700
Unconsolidated VIEs
Transfers of Financial Assets [Line Items]
Retained interests: principal and interest received	114	$ 143
Unconsolidated VIEs | Single Class MBS, REMIC & Megas
Transfers of Financial Assets [Line Items]
Retained interests: unpaid principal balance	1,500		$ 1,100
Retained interests: fair value	$ 2,200		$ 2,000