Allowance for Loan and Lease Losses - Schedule of Allowance for Loan and Lease Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan and lease losses, beginning balance	$ 1,637	$ 850	$ 922	$ 178
Initial PCD ALLL	0		220	272
Initial PCD ALLL		0
Day 2 provision for loan and lease losses	0	0	462	454
Provision for credit losses - loans and leases	212	50	452	33
Total provision for loan and lease losses	212	50	914	487
Charge-offs	(199)	(33)	(437)	(107)
Recoveries	23	15	54	52
Allowance for loan and lease losses, ending balance	1,673	882	1,673	882
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan and lease losses, beginning balance	915	740	789	80
Initial PCD ALLL	0		0	258
Initial PCD ALLL		0
Day 2 provision for loan and lease losses	0	0	0	432
Provision for credit losses - loans and leases	149	43	379	53
Total provision for loan and lease losses	149	43	379	485
Charge-offs	(85)	(28)	(209)	(92)
Recoveries	12	11	32	35
Allowance for loan and lease losses, ending balance	991	766	991	766
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan and lease losses, beginning balance	156	110	133	98
Initial PCD ALLL	0	0	0	14
Day 2 provision for loan and lease losses	0	0	0	22
Provision for credit losses - loans and leases		7	18
(Benefit) for credit losses - loans and leases	(11)			(20)
Total provision for loan and lease losses	(11)	7	18	2
Charge-offs	(7)	(5)	(20)	(15)
Recoveries	4	4	11	17
Allowance for loan and lease losses, ending balance	142	116	142	116
SVB
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan and lease losses, beginning balance	566	0	0	0
Initial PCD ALLL	0	0	220	0
Day 2 provision for loan and lease losses	0	0	462	0
Provision for credit losses - loans and leases	74	0	55	0
Total provision for loan and lease losses	74	0	517	0
Charge-offs	(107)	0	(208)	0
Recoveries	7	0	11	0
Allowance for loan and lease losses, ending balance	$ 540	$ 0	$ 540	$ 0