Loans and Leases - Schedule of Delinquency Status of Our Loans Held for Investment (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	$ 60,987	$ 60,732
Non-Accrual Loans	2,800	2,975
Current
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	57,768	56,771
Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	368	986
Loans 90 Days or More Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	51	0
Loans and leases held for investment: \| Multi-family
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	26,931	28,983
Non-Accrual Loans	2,132	2,261
Loans and leases held for investment: \| Multi-family \| Current
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	24,528	26,134
Loans and leases held for investment: \| Multi-family \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	233	588
Loans and leases held for investment: \| Multi-family \| Loans 90 Days or More Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	38	0
Loans and leases held for investment: \| Commercial real estate
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	8,244	9,314
Non-Accrual Loans	471	489
Loans and leases held for investment: \| Commercial real estate \| Current
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	7,730	8,670
Loans and leases held for investment: \| Commercial real estate \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	30	155
Loans and leases held for investment: \| Commercial real estate \| Loans 90 Days or More Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	13	0
Loans and leases held for investment: \| One-to-four family first mortgage
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	5,767	5,630
Non-Accrual Loans	60	64
Loans and leases held for investment: \| One-to-four family first mortgage \| Current
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	5,698	5,488
Loans and leases held for investment: \| One-to-four family first mortgage \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	9	78
Loans and leases held for investment: \| One-to-four family first mortgage \| Loans 90 Days or More Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	0	0
Commercial and industrial \| Commercial and industrial
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	18,563	15,217
Non-Accrual Loans	111	130
Commercial and industrial \| Commercial and industrial \| Current
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	18,370	14,961
Commercial and industrial \| Commercial and industrial \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	82	126
Commercial and industrial \| Commercial and industrial \| Loans 90 Days or More Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	0	0
Commercial and industrial \| Other
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	1,482	1,588
Non-Accrual Loans	26	31
Commercial and industrial \| Other \| Current
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	1,442	1,518
Commercial and industrial \| Other \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	14	39
Commercial and industrial \| Other \| Loans 90 Days or More Past Due and Still Accruing
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	$ 0	$ 0