Loans and Leases - Quality of Loans Held for Investment (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	$ 71,116	$ 84,619
Non-Accrual Loans	2,514	428
Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	261	250
Remaining
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	68,341	83,941
Loans and Leases Held for Investment: \| Multi-family
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	35,140	37,265
Non-Accrual Loans	1,504	138
Loans and Leases Held for Investment: \| Multi-family \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	124	121
Loans and Leases Held for Investment: \| Multi-family \| Remaining
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	33,512	37,006
Loans and Leases Held for Investment: \| Commercial real estate
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	9,217	10,470
Non-Accrual Loans	692	128
Loans and Leases Held for Investment: \| Commercial real estate \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	43	28
Loans and Leases Held for Investment: \| Commercial real estate \| Remaining
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	8,482	10,314
Loans and Leases Held for Investment: \| One-to-four family first mortgage
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	5,247	6,061
Non-Accrual Loans	39	95
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	21	40
Loans and Leases Held for Investment: \| One-to-four family first mortgage \| Remaining
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	5,187	5,926
Loans and Leases Held for Investment: \| Acquisition, development, and construction
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	3,265	2,912
Non-Accrual Loans	21	2
Loans and Leases Held for Investment: \| Acquisition, development, and construction \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	16	2
Loans and Leases Held for Investment: \| Acquisition, development, and construction \| Remaining
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	3,228	2,908
Other loans held for investment \| Commercial and industrial loans and lease financing
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	16,474	25,254
Non-Accrual Loans	235	43
Other loans held for investment \| Commercial and industrial loans and lease financing \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	47	37
Other loans held for investment \| Commercial and industrial loans and lease financing \| Remaining
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	16,192	25,174
Other loans held for investment \| Other
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	1,773	2,657
Non-Accrual Loans	23	22
Other loans held for investment \| Other \| Loans 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	10	22
Other loans held for investment \| Other \| Remaining
Financing Receivable, Recorded Investment, Past Due
Total Loans Receivable	$ 1,740	$ 2,613

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
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-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-14

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