Allowance for Credit Losses on Loans and Leases - Additional Information about Nonaccrual Loans (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Impaired [Line Items]
Non-accrual loans with no related allowance:	$ 2,681	$ 1,636
Non-accrual loans with an allowance recorded:	560	979
Total non-accrual loans	3,241	2,615
Related Allowance	168	164
Mortgage Loans Held for Investment | Multi-family
Financing Receivable, Impaired [Line Items]
Non-accrual loans with no related allowance:	2,148	1,092
Non-accrual loans with an allowance recorded:	292	663
Total non-accrual loans	2,440	1,755
Related Allowance	47	77
Mortgage Loans Held for Investment | Commercial real estate
Financing Receivable, Impaired [Line Items]
Non-accrual loans with no related allowance:	394	429
Non-accrual loans with an allowance recorded:	157	135
Total non-accrual loans	551	564
Related Allowance	56	31
Mortgage Loans Held for Investment | One-to-four family first mortgage
Financing Receivable, Impaired [Line Items]
Non-accrual loans with no related allowance:	52	61
Non-accrual loans with an allowance recorded:	18	9
Total non-accrual loans	70	70
Related Allowance	2	1
Other
Financing Receivable, Impaired [Line Items]
Non-accrual loans with no related allowance:	0	3
Non-accrual loans with an allowance recorded:	26	21
Total non-accrual loans	26	24
Related Allowance	23	55
Other | Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Non-accrual loans with no related allowance:	87	51
Non-accrual loans with an allowance recorded:	67	151
Total non-accrual loans	154	202
Related Allowance	$ 40	$ 0