Loans and Leases - Loan Modifications (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 19		$ 65	$ 45
Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 8		$ 52	$ 35
Percent of Total Loan class	0.08%		0.49%
Interest rate reduction, weighted-average contractual interest rate, prior to modification		4.75%		6.00%
Interest rate reduction, weighted-average contractual interest rate, after modification		9.75%		4.00%
Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 4		$ 6
Percent of Total Loan class	0.07%		0.10%
Other Loans: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 7		$ 7	$ 4
Percent of Total Loan class	0.03%		0.03%
Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 8		$ 52
Interest Rate Reduction | Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 8		$ 52
Interest rate reduction, weighted-average contractual interest rate, prior to modification	8.00%		10.09%
Interest rate reduction, weighted-average contractual interest rate, after modification	4.00%		4.00%
Interest Rate Reduction | Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 0		$ 0
Interest rate reduction, weighted-average contractual interest rate, prior to modification	6.05%		5.47%
Interest rate reduction, weighted-average contractual interest rate, after modification	4.80%		4.40%
Interest Rate Reduction | Other Loans: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 0		$ 0
Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	9		10
Term Extension | Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	0		0
Term Extension | Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 2		$ 3
Weighted-average Term (in years)	13 years 7 months 6 days		13 years
Term Extension | Mortgage Loans: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average Term (in years)	9 months 3 days		9 months 3 days
Term Extension | Other Loans: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 7		$ 7
Combination - Interest Rate Reduction & Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	2		3
Combination - Interest Rate Reduction & Term Extension | Mortgage Loans: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	0		0
Combination - Interest Rate Reduction & Term Extension | Mortgage Loans: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	2		3
Combination - Interest Rate Reduction & Term Extension | Other Loans: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 0		$ 0