Loans and Leases - Performance of Loans Modified in Last 12 Months (Details) - USD ($) $ in Millions	Jun. 30, 2025	Jun. 30, 2024
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 28	$ 256
Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	11	58
30 - 89 Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0	102
90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	17	96
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 | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total		26
Loans and leases held for investment: | Multi-family | 30 - 89 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	6	102
Loans and leases held for investment: | Commercial real estate | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	6	21
Loans and leases held for investment: | Commercial real estate | 30 - 89 Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0	3
Loans and leases held for investment: | Commercial real estate | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0	78
Loans and leases held for investment: | One-to-four family first mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	21	17
Loans and leases held for investment: | One-to-four family first mortgage | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	5	8
Loans and leases held for investment: | One-to-four family first mortgage | 30 - 89 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	16	9
Other loans held for investment | Commercial and Industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	1	13
Other loans held for investment | Commercial and Industrial | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0	3
Other loans held for investment | Commercial and Industrial | 30 - 89 Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	0	2
Other loans held for investment | Commercial and Industrial | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total	$ 1	8
Other loans held for investment | Other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total		1
Other loans held for investment | Other | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total		0
Other loans held for investment | Other | 30 - 89 Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total		0
Other loans held for investment | Other | 90+ Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total		$ 1