Variable Interest Entities - Re-securitizations (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 securities to VIEs
U.S. GSEs and government agencies	$ 4,521	$ 1,417	$ 14,188	$ 14,866
U.S. GSEs and government agencies | Nonconsolidated re-securitization VIEs
Variable Interest Entity [Line Items]
Interest in VIEs	$ 3,287		$ 3,287		$ 2,580