Commitments, Contingent Liabilities and Guarantees - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Written Put Options
Commitments Contingencies And Guarantees [Line Items]
Weighted average life of written put options	2 years 2 months 12 days
Standby letters of credit
Commitments Contingencies And Guarantees [Line Items]
Remaining weighted-average life of standby letters of credit in years	2 years
Underwriting And Servicing Program
Commitments Contingencies And Guarantees [Line Items]
Weighted-average remaining term for outstanding commercial mortgage loans in years	7 years 9 months 18 days
Unpaid principal balance outstanding of loans sold	$ 21,000
Maximum potential amount of undiscounted future payments that could be required, percentage of principal balance of loans outstanding	31.00%
Residential mortgage reserve
Commitments Contingencies And Guarantees [Line Items]
Unpaid principal balance outstanding of loans sold	$ 10,200
Maximum potential amount of undiscounted future payments that could be required, percentage of principal balance of loans outstanding	30.00%
Liability for estimated repurchase obligations on loans sold	$ 15
Minimum | Standby letters of credit
Commitments Contingencies And Guarantees [Line Items]
Remaining actual life letters of credit in years	1 year
Minimum | Low
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, probability of payment	0.00%
Minimum | Moderate
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, probability of payment	30.00%
Minimum | High
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, probability of payment	70.00%
Maximum | Standby letters of credit
Commitments Contingencies And Guarantees [Line Items]
Remaining actual life letters of credit in years	12 years 10 months 24 days
Maximum | Low
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, probability of payment	30.00%
Maximum | Moderate
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, probability of payment	70.00%