Loans and Leases - Performance of Loans Modified in Last 12 Months (Details) - USD ($) $ in Millions	Jun. 30, 2024	Jun. 30, 2023
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 256	$ 6
Remaining
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	58	0
Loans 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	102	0
90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	96	6
Loans and Leases Held for Investment: | Multi-family
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	123
Loans and Leases Held for Investment: | Multi-family | Remaining
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	26
Loans and Leases Held for Investment: | Multi-family | Loans 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	97
Loans and Leases Held for Investment: | Multi-family | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Loans and Leases Held for Investment: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	102
Loans and Leases Held for Investment: | Commercial real estate | Remaining
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	21
Loans and Leases Held for Investment: | Commercial real estate | Loans 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	3
Loans and Leases Held for Investment: | Commercial real estate | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	78
Loans and Leases Held for Investment: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	17	6
Loans and Leases Held for Investment: | One-to-four family first mortgage | Remaining
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	8	0
Loans and Leases Held for Investment: | One-to-four family first mortgage | Loans 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0	0
Loans and Leases Held for Investment: | One-to-four family first mortgage | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	9	$ 6
Other loans held for investment | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	13
Other loans held for investment | Commercial and industrial | Remaining
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	3
Other loans held for investment | Commercial and industrial | Loans 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	2
Other loans held for investment | Commercial and industrial | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	8
Other loans held for investment | Other Consumer
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1
Other loans held for investment | Other Consumer | Remaining
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Other loans held for investment | Other Consumer | Loans 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0
Other loans held for investment | Other Consumer | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 1