Loans and Leases - Loan Modifications (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 46	$ 47
Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 44	$ 35
Percent of Total Loan class	0.42%
Interest rate reduction, weighted-average contractual interest rate, prior to modification	6.00%
Interest rate reduction, weighted-average contractual interest rate, after modification	4.00%
Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 2
Percent of Total Loan class	0.03%
Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 44
Interest Rate Reduction | Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 44
Interest rate reduction, weighted-average contractual interest rate, prior to modification	10.50%
Interest rate reduction, weighted-average contractual interest rate, after modification	4.00%
Interest Rate Reduction | Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 0
Interest rate reduction, weighted-average contractual interest rate, prior to modification	4.84%
Interest rate reduction, weighted-average contractual interest rate, after modification	3.97%
Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 1
Term Extension | Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	0
Term Extension | Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 1
Weighted-average Term (in years)	12 years 8 months 12 days
Combination - Interest Rate Reduction & Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 1
Combination - Interest Rate Reduction & Term Extension | Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	0
Combination - Interest Rate Reduction & Term Extension | Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 1