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
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Residential mortgage loans held for sale
Total principal balance	$ 38,540		$ 39,016
Delinquent loans	310		329
Net charge-offs	1	$ 2
Commercial mortgage loans held for sale
Total principal balance	56,409		57,492
Delinquent loans	92		$ 89
Net charge-offs	$ 61	$ 4