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, 2025	Mar. 31, 2024	Dec. 31, 2024
Residential mortgage loans held for sale
Total principal balance	$ 37,276		$ 37,619
Delinquent loans	284		288
Net charge-offs	1	$ 1
Commercial mortgage loans held for sale
Total principal balance	54,055		51,274
Delinquent loans	352		$ 124
Net charge-offs	$ 10	$ 61