Loans and Leases - Loans Held for Investment by Credit Quality Indicator (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Recorded Investment
Total	$ 84,619	$ 69,001
Other
Financing Receivable, Recorded Investment
Total	27,911	14,528
Mortgage Loans
Financing Receivable, Recorded Investment
Total	56,708	54,473
Mortgage Loans | Pass
Financing Receivable, Recorded Investment
Total	51,057	52,195
Mortgage Loans | Special mention
Financing Receivable, Recorded Investment
Total	1,192	1,106
Mortgage Loans | Substandard
Financing Receivable, Recorded Investment
Total	4,459	1,172
Mortgage Loans | Doubtful
Financing Receivable, Recorded Investment
Total	0
Mortgage Loans | Multi-family
Financing Receivable, Recorded Investment
Total	37,265	38,130
Mortgage Loans | Multi-family | Pass
Financing Receivable, Recorded Investment
Total	34,170	36,622
Mortgage Loans | Multi-family | Special mention
Financing Receivable, Recorded Investment
Total	768	864
Mortgage Loans | Multi-family | Substandard
Financing Receivable, Recorded Investment
Total	2,327	644
Mortgage Loans | Multi-family | Doubtful
Financing Receivable, Recorded Investment
Total	0
Mortgage Loans | Commercial real estate
Financing Receivable, Recorded Investment
Total	10,470	8,526
Mortgage Loans | Commercial real estate | Pass
Financing Receivable, Recorded Investment
Total	8,734	7,871
Mortgage Loans | Commercial real estate | Special mention
Financing Receivable, Recorded Investment
Total	367	230
Mortgage Loans | Commercial real estate | Substandard
Financing Receivable, Recorded Investment
Total	1,369	425
Mortgage Loans | Commercial real estate | Doubtful
Financing Receivable, Recorded Investment
Total	0
Mortgage Loans | One-to-four family first mortgage
Financing Receivable, Recorded Investment
Total	6,061	5,821
Mortgage Loans | One-to-four family first mortgage | Pass
Financing Receivable, Recorded Investment
Total	5,328	5,710
Mortgage Loans | One-to-four family first mortgage | Special mention
Financing Receivable, Recorded Investment
Total	0	8
Mortgage Loans | One-to-four family first mortgage | Substandard
Financing Receivable, Recorded Investment
Total	733	103
Mortgage Loans | One-to-four family first mortgage | Doubtful
Financing Receivable, Recorded Investment
Total	0
Mortgage Loans | Acquisition, development, and construction
Financing Receivable, Recorded Investment
Total	2,912	1,996
Mortgage Loans | Acquisition, development, and construction | Pass
Financing Receivable, Recorded Investment
Total	2,825	1,992
Mortgage Loans | Acquisition, development, and construction | Special mention
Financing Receivable, Recorded Investment
Total	57	4
Mortgage Loans | Acquisition, development, and construction | Substandard
Financing Receivable, Recorded Investment
Total	30	0
Mortgage Loans | Acquisition, development, and construction | Doubtful
Financing Receivable, Recorded Investment
Total	0
Other Loans:
Financing Receivable, Recorded Investment
Total	27,911	14,528
Other Loans: | Pass
Financing Receivable, Recorded Investment
Total	27,317	14,446
Other Loans: | Special mention
Financing Receivable, Recorded Investment
Total	335	18
Other Loans: | Substandard
Financing Receivable, Recorded Investment
Total	259	64
Other Loans: | Doubtful
Financing Receivable, Recorded Investment
Total	0
Other Loans: | Commercial and industrial loans and lease financing
Financing Receivable, Recorded Investment
Total	25,254	12,276
Other Loans: | Commercial and industrial loans and lease financing | Pass
Financing Receivable, Recorded Investment
Total	24,683	12,208
Other Loans: | Commercial and industrial loans and lease financing | Special mention
Financing Receivable, Recorded Investment
Total	335	18
Other Loans: | Commercial and industrial loans and lease financing | Substandard
Financing Receivable, Recorded Investment
Total	236	50
Other Loans: | Commercial and industrial loans and lease financing | Doubtful
Financing Receivable, Recorded Investment
Total	0
Other Loans: | Other
Financing Receivable, Recorded Investment
Total	2,657	2,252
Other Loans: | Other | Pass
Financing Receivable, Recorded Investment
Total	2,634	2,238
Other Loans: | Other | Special mention
Financing Receivable, Recorded Investment
Total	0	0
Other Loans: | Other | Substandard
Financing Receivable, Recorded Investment
Total	23	$ 14
Other Loans: | Other | Doubtful
Financing Receivable, Recorded Investment
Total	$ 0