Allowance for Credit Losses on Loans and Leases - Activity in the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 1,106	$ 1,268	$ 1,201	$ 992	$ 992
Charge-offs	(92)	(260)	(356)	(705)
Recoveries	19	21	51	35
Provision for (recovery of) credit losses on loans and leases	38	235	175	942
Balance, end of period	1,071	1,264	1,071	1,264	1,201
Loans and leases held for investment: | Multi-family
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	538	618	639	307	307
Charge-offs	(53)	(101)	(238)	(188)	(308)
Recoveries	7	3	16	4
Provision for (recovery of) credit losses on loans and leases	66	104	141	501
Balance, end of period	558	624	558	624	639
Loans and leases held for investment: | Commercial Real Estate
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	318	371	304	402	402
Charge-offs	(19)	(114)	(41)	(415)	(466)
Recoveries	1	6	8	6
Provision for (recovery of) credit losses on loans and leases	(45)	79	(16)	349
Balance, end of period	255	342	255	342	304
Loans and leases held for investment: | One-to-Four Family First Mortgage
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	33	40	39	47	47
Charge-offs	(1)	(7)	(3)	(8)	(8)
Recoveries	0	5	0	5
Provision for (recovery of) credit losses on loans and leases	2	4	(2)	(2)
Balance, end of period	34	42	34	42	39
Loans and leases held for investment: | Commercial and Industrial
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Charge-offs			(50)		(136)
Other
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	57	66	68	102	102
Charge-offs	(10)	(5)	(24)	(15)
Recoveries	3	2	9	4
Provision for (recovery of) credit losses on loans and leases	17	6	14	(22)
Balance, end of period	67	69	67	69	68
Other | Commercial and Industrial
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	160	173	151	134	134
Charge-offs	(9)	(33)	(50)	(79)
Recoveries	8	5	18	16
Provision for (recovery of) credit losses on loans and leases	(2)	42	38	116
Balance, end of period	$ 157	$ 187	$ 157	$ 187	$ 151