Loans and Leases - Loan Modifications (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 5	$ 19	$ 29	$ 65
Loans and Leases Held for Investment: | Multi-family
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost			$ 2
Percent of Total Loan class			0.01%
Loans and Leases Held for Investment: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		$ 8	$ 12	$ 52
Percent of Total Loan class		0.08%	0.12%	0.49%
Loans and Leases Held for Investment: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 5	$ 4	$ 7	$ 6
Percent of Total Loan class	0.09%	0.07%	0.12%	0.10%
Other loans held for investment | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		$ 7	$ 8	$ 7
Percent of Total Loan class		0.03%	0.04%	0.03%
Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 0	$ 8	$ 10	$ 52
Interest Rate Reduction | Loans and Leases Held for Investment: | Multi-family
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost			$ 2
Interest Rate Reduction | Loans and Leases Held for Investment: | Multi-family | Minimum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate			8.08%
Interest Rate Reduction | Loans and Leases Held for Investment: | Multi-family | Maximum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate			6.00%
Interest Rate Reduction | Loans and Leases Held for Investment: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		$ 8	$ 8	$ 52
Interest Rate Reduction | Loans and Leases Held for Investment: | Commercial real estate | Minimum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate		8.00%	8.13%	10.09%
Interest Rate Reduction | Loans and Leases Held for Investment: | Commercial real estate | Maximum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate		4.00%	7.00%	4.00%
Interest Rate Reduction | Loans and Leases Held for Investment: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 0	$ 0	$ 0	$ 0
Weighted-average Term (in years)	10 years 6 months 21 days	13 years 7 months 6 days	12 years 2 months 12 days	13 years
Interest Rate Reduction | Loans and Leases Held for Investment: | One-to-four family first mortgage | Minimum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate	4.76%	6.05%	4.69%	5.47%
Interest Rate Reduction | Loans and Leases Held for Investment: | One-to-four family first mortgage | Maximum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate	3.65%	4.80%	3.70%	4.40%
Interest Rate Reduction | Loans and Leases Held for Investment: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average Term (in years)	1 year	9 months 3 days	4 months 24 days	9 months 3 days
Interest Rate Reduction | Loans and Leases Held for Investment: | Commercial and industrial | Minimum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate	8.51%	0.00%	7.44%	0.00%
Interest Rate Reduction | Loans and Leases Held for Investment: | Commercial and industrial | Maximum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate	6.00%	0.00%	6.30%	0.00%
Interest Rate Reduction | Loans and Leases Held for Investment: | Other Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average Term (in years)			1 year 9 months 18 days
Interest Rate Reduction | Loans and Leases Held for Investment: | Other Consumer | Minimum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate			10.72%
Interest Rate Reduction | Loans and Leases Held for Investment: | Other Consumer | Maximum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Weighted-average contractual interest rate			4.30%
Interest Rate Reduction | Other loans held for investment | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		$ 0	$ 0	$ 0
Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 4	9	16	10
Term Extension | Loans and Leases Held for Investment: | Multi-family
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost			0
Term Extension | Loans and Leases Held for Investment: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		0	4	0
Term Extension | Loans and Leases Held for Investment: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	4	2	5	3
Term Extension | Other loans held for investment | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		7	7	7
Combination - Interest Rate Reduction & Term Extension
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	1	2	3	3
Combination - Interest Rate Reduction & Term Extension | Loans and Leases Held for Investment: | Multi-family
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost			0
Combination - Interest Rate Reduction & Term Extension | Loans and Leases Held for Investment: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		0	0	0
Combination - Interest Rate Reduction & Term Extension | Loans and Leases Held for Investment: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost	$ 1	2	2	3
Combination - Interest Rate Reduction & Term Extension | Other loans held for investment | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Amortized Cost		$ 0	$ 1	$ 0