BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 1,796	$ 1,990	$ 5,434	$ 4,801
Provision (benefit) for credit losses	117	192	276	1,126
Net interest income after provision for credit losses	1,679	1,798	5,158	3,675
Noninterest income	650	615	1,916	11,532
Noninterest expense	1,456	1,416	4,218	3,843
Income before income taxes	873	997	2,856	11,364
Income tax expense (benefit)	234	245	779	412
Net income	639	752	2,077	10,952
Loans and leases	138,695	133,202	138,695	133,202	$ 133,302
Operating lease equipment, net	9,186	8,661	9,186	8,661	8,746
Deposits	151,574	146,233	151,574	146,233	$ 145,854
Operating Segments | General Bank
Segment Reporting Information [Line Items]
Net interest income (expense)	768	681	2,197	1,889
Provision (benefit) for credit losses	38	24	121	40
Net interest income after provision for credit losses	730	657	2,076	1,849
Noninterest income	149	135	446	388
Noninterest expense	517	482	1,534	1,349
Income before income taxes	362	310	988	888
Income tax expense (benefit)	99	85	270	222
Net income	263	225	718	666
Loans and leases	66,092	61,035	66,092	61,035
Operating lease equipment, net	0	0	0	0
Deposits	72,169	69,108	72,169	69,108
Operating Segments | Commercial Bank
Segment Reporting Information [Line Items]
Net interest income (expense)	274	249	823	744
Provision (benefit) for credit losses	29	132	65	353
Net interest income after provision for credit losses	245	117	758	391
Noninterest income	133	139	400	420
Noninterest expense	227	205	676	615
Income before income taxes	151	51	482	196
Income tax expense (benefit)	41	14	127	55
Net income	110	37	355	141
Loans and leases	32,689	30,220	32,689	30,220
Operating lease equipment, net	767	739	767	739
Deposits	2,754	3,370	2,754	3,370
Operating Segments | SVB Commercial
Segment Reporting Information [Line Items]
Net interest income (expense)	583	537	1,706	1,128
Provision (benefit) for credit losses	50	39	90	17
Net interest income after provision for credit losses	533	498	1,616	1,111
Noninterest income	139	141	415	295
Noninterest expense	393	413	1,164	900
Income before income taxes	279	226	867	506
Income tax expense (benefit)	75	61	235	136
Net income	204	165	632	370
Loans and leases	39,852	41,906	39,852	41,906
Operating lease equipment, net	0	0	0	0
Deposits	35,945	36,236	35,945	36,236
Operating Segments | Rail
Segment Reporting Information [Line Items]
Net interest income (expense)	(48)	(40)	(136)	(101)
Provision (benefit) for credit losses	0	0	0	0
Net interest income after provision for credit losses	(48)	(40)	(136)	(101)
Noninterest income	207	194	612	549
Noninterest expense	130	116	374	357
Income before income taxes	29	38	102	91
Income tax expense (benefit)	8	10	27	23
Net income	21	28	75	68
Loans and leases	62	41	62	41
Operating lease equipment, net	8,419	7,922	8,419	7,922
Deposits	14	12	14	12
Corporate
Segment Reporting Information [Line Items]
Net interest income (expense)	219	563	844	1,141
Provision (benefit) for credit losses	0	(3)	0	716
Net interest income after provision for credit losses	219	566	844	425
Noninterest income	22	6	43	9,880
Noninterest expense	189	200	470	622
Income before income taxes	52	372	417	9,683
Income tax expense (benefit)	11	75	120	(24)
Net income	41	297	297	9,707
Loans and leases	0	0	0	0
Operating lease equipment, net	0	0	0	0
Deposits	$ 40,692	$ 37,507	$ 40,692	$ 37,507