Mortgage Servicing Rights - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Transfers and Servicing [Abstract]
Mortgage servicing rights	$ 3,400	$ 3,400
Contractually specified servicing fee, late fee, and ancillary fee earned in exchange for servicing financial asset	$ 2
Fixed Rate Conventional Loans
Servicing Asset Key Economic Assumptions [Line Items]
Risk premium on 10-year U.S. Treasury	0.0700
Loans Excluding Fixed Rate Conventional Loans
Servicing Asset Key Economic Assumptions [Line Items]
Risk premium on 10-year U.S. Treasury	0.0800