SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	$ 1,695	$ 1,821	$ 3,358	$ 3,638
Rental income on operating lease equipment	272	259	542	514
All other noninterest income	406	380	771	752
Total noninterest income	678	639	1,313	1,266
Total income	2,373	2,460	4,671	4,904
Depreciation on operating lease equipment	100	98	198	194
Maintenance and other operating lease expenses	55	60	113	105
Personnel cost	810	745	1,628	1,489
Acquisition-related expenses	38	44	80	102
All other noninterest expense	497	439	974	872
Total noninterest expense	1,500	1,386	2,993	2,762
Provision for credit losses	115	95	269	159
Income before income taxes	758	979	1,409	1,983
Income tax expense (benefit)	183	272	351	545
Net income	575	707	1,058	1,438
Loans and leases	141,269	139,341	141,269	139,341	$ 140,221
Operating lease equipment, net	9,466	8,945	9,466	8,945	9,323
Interest on investment securities	419	330	833	612
Deposits	159,935	151,079	159,935	151,079	$ 155,229
Operating Segments | General Bank
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	824	730	1,612	1,414
Rental income on operating lease equipment	0	0	0	0
All other noninterest income	164	152	328	297
Total noninterest income	164	152	328	297
Total income	988	882	1,940	1,711
Depreciation on operating lease equipment	0	0	0	0
Maintenance and other operating lease expenses	0	0	0	0
Personnel cost	210	185	424	392
Acquisition-related expenses	0	0	0	0
All other noninterest expense	370	316	721	637
Total noninterest expense	580	501	1,145	1,029
Provision for credit losses	13	37	59	58
Income before income taxes	395	344	736	624
Income tax expense (benefit)	101	92	189	171
Net income	294	252	547	453
Loans and leases	64,987	63,327	64,987	63,327
Operating lease equipment, net	0	0	0	0
Deposits	73,499	71,261	73,499	71,261
Operating Segments | Commercial Bank
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	299	311	592	611
Rental income on operating lease equipment	54	58	110	115
All other noninterest income	98	77	167	160
Total noninterest income	152	135	277	275
Total income	451	446	869	886
Depreciation on operating lease equipment	44	48	88	94
Maintenance and other operating lease expenses	0	0	0	0
Personnel cost	69	63	141	137
Acquisition-related expenses	0	0	0	0
All other noninterest expense	154	135	313	275
Total noninterest expense	267	246	542	506
Provision for credit losses	47	39	132	59
Income before income taxes	137	161	195	321
Income tax expense (benefit)	35	44	50	86
Net income	102	117	145	235
Loans and leases	38,691	36,835	38,691	36,835
Operating lease equipment, net	750	767	750	767
Deposits	2,899	3,294	2,899	3,294
Operating Segments | SVB Commercial
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	490	553	983	1,076
Rental income on operating lease equipment	0	0	0	0
All other noninterest income	130	134	262	268
Total noninterest income	130	134	262	268
Total income	620	687	1,245	1,344
Depreciation on operating lease equipment	0	0	0	0
Maintenance and other operating lease expenses	0	0	0	0
Personnel cost	110	123	224	242
Acquisition-related expenses	0	0	0	0
All other noninterest expense	272	246	537	493
Total noninterest expense	382	369	761	735
Provision for credit losses	55	19	78	42
Income before income taxes	183	299	406	567
Income tax expense (benefit)	47	85	104	160
Net income	136	214	302	407
Loans and leases	37,529	39,117	37,529	39,117
Operating lease equipment, net	0	0	0	0
Deposits	37,798	35,773	37,798	35,773
Operating Segments | Rail
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	(53)	(45)	(105)	(88)
Rental income on operating lease equipment	218	201	432	399
All other noninterest income	3	2	5	6
Total noninterest income	221	203	437	405
Total income	168	158	332	317
Depreciation on operating lease equipment	56	50	110	100
Maintenance and other operating lease expenses	55	60	113	105
Personnel cost	6	6	14	14
Acquisition-related expenses	0	0	0	0
All other noninterest expense	26	15	40	29
Total noninterest expense	143	131	277	248
Provision for credit losses	0	0	0	0
Income before income taxes	25	27	55	69
Income tax expense (benefit)	6	8	14	19
Net income	19	19	41	50
Loans and leases	62	62	62	62
Operating lease equipment, net	8,716	8,178	8,716	8,178
Deposits	3	10	3	10
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Net interest income (expense)	135	272	276	625
Rental income on operating lease equipment	0	0	0	0
All other noninterest income	11	15	9	21
Total noninterest income	11	15	9	21
Total income	146	287	285	646
Depreciation on operating lease equipment	0	0	0	0
Maintenance and other operating lease expenses	0	0	0	0
Personnel cost	415	368	825	704
Acquisition-related expenses	38	44	80	102
All other noninterest expense	(325)	(273)	(637)	(562)
Total noninterest expense	128	139	268	244
Provision for credit losses	0	0	0	0
Income before income taxes	18	148	17	402
Income tax expense (benefit)	(6)	43	(6)	109
Net income	24	105	23	293
Loans and leases	0	0	0	0
Operating lease equipment, net	0	0	0	0
Deposits	$ 45,736	$ 40,741	$ 45,736	$ 40,741