SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	$ 1,663	$ 1,817
Rental income on operating lease equipment	270	255
All other noninterest income	365	372
Total noninterest income	635	627
Total income	2,298	2,444
Depreciation on operating lease equipment	98	96
Maintenance and other operating lease expenses	58	45
Personnel cost	818	744
Acquisition-related expenses	42	58
All other noninterest expense	477	433
Total noninterest expense	1,493	1,376
Provision for credit losses	154	64
Income (loss) before income taxes	651	1,004
Income tax expense	168	273
Net income	483	731
Loans and leases	141,358	135,370	$ 140,221
Operating lease equipment, net	9,371	8,811	9,323
Deposits	159,325	149,609	$ 155,229
Operating Segments | General Bank
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	788	684
Rental income on operating lease equipment	0	0
All other noninterest income	164	145
Total noninterest income	164	145
Total income	952	829
Depreciation on operating lease equipment	0	0
Maintenance and other operating lease expenses	0	0
Personnel cost	214	207
Acquisition-related expenses	0	0
All other noninterest expense	351	321
Total noninterest expense	565	528
Provision for credit losses	46	21
Income (loss) before income taxes	341	280
Income tax expense	88	79
Net income	253	201
Loans and leases	64,847	62,015
Operating lease equipment, net	0	0
Deposits	74,309	70,908
Operating Segments | Commercial Bank
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	293	300
Rental income on operating lease equipment	56	57
All other noninterest income	69	83
Total noninterest income	125	140
Total income	418	440
Depreciation on operating lease equipment	44	46
Maintenance and other operating lease expenses	0	0
Personnel cost	72	74
Acquisition-related expenses	0	0
All other noninterest expense	159	140
Total noninterest expense	275	260
Provision for credit losses	85	20
Income (loss) before income taxes	58	160
Income tax expense	15	42
Net income	43	118
Loans and leases	38,631	36,251
Operating lease equipment, net	731	763
Deposits	2,994	3,400
Operating Segments | SVB Commercial
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	493	523
Rental income on operating lease equipment	0	0
All other noninterest income	132	134
Total noninterest income	132	134
Total income	625	657
Depreciation on operating lease equipment	0	0
Maintenance and other operating lease expenses	0	0
Personnel cost	114	119
Acquisition-related expenses	0	0
All other noninterest expense	265	247
Total noninterest expense	379	366
Provision for credit losses	23	23
Income (loss) before income taxes	223	268
Income tax expense	57	75
Net income	166	193
Loans and leases	37,818	37,042
Operating lease equipment, net	0	0
Deposits	37,020	33,879
Operating Segments | Rail
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	(52)	(43)
Rental income on operating lease equipment	214	198
All other noninterest income	2	4
Total noninterest income	216	202
Total income	164	159
Depreciation on operating lease equipment	54	50
Maintenance and other operating lease expenses	58	45
Personnel cost	8	8
Acquisition-related expenses	0	0
All other noninterest expense	14	14
Total noninterest expense	134	117
Provision for credit losses	0	0
Income (loss) before income taxes	30	42
Income tax expense	8	11
Net income	22	31
Loans and leases	62	62
Operating lease equipment, net	8,640	8,048
Deposits	12	14
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	141	353
Rental income on operating lease equipment	0	0
All other noninterest income	(2)	6
Total noninterest income	(2)	6
Total income	139	359
Depreciation on operating lease equipment	0	0
Maintenance and other operating lease expenses	0	0
Personnel cost	410	336
Acquisition-related expenses	42	58
All other noninterest expense	(312)	(289)
Total noninterest expense	140	105
Provision for credit losses	0	0
Income (loss) before income taxes	(1)	254
Income tax expense	0	66
Net income	(1)	188
Loans and leases	0	0
Operating lease equipment, net	0	0
Deposits	$ 44,990	$ 41,408