Loan Sale and Servicing Activities and Variable Interest Entities (Principal Balance, Delinquent Loans (Loans 90 Days or More Past Due), and Net Charge-Offs Related to Serviced Loans) (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
Residential mortgage loans held for sale
Total principal balance	$ 39,542		$ 39,542		$ 41,031
Delinquent loans	324		324		346
Net charge-offs		$ 1	2	$ 3
Commercial mortgage loans held for sale
Total principal balance	58,761		58,761		57,974
Delinquent loans
Net charge-offs	$ 14	$ 9	$ 18	$ 12