BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 1,821	$ 1,961	$ 3,638	$ 2,811
Provision (benefit) for credit losses	95	151	159	934
Net interest income after provision for credit losses	1,726	1,810	3,479	1,877
Noninterest income	639	658	1,266	10,917
Noninterest expense	1,386	1,572	2,762	2,427
Income before income taxes	979	896	1,983	10,367
Income tax expense (benefit)	272	214	545	167
Net income	707	682	1,438	10,200
Loans and leases	139,341	133,015	139,341	133,015	$ 133,302
Operating lease equipment, net	8,945	8,531	8,945	8,531	8,746
Deposits	151,079	141,164	151,079	141,164	$ 145,854
Operating Segments | General Bank
Segment Reporting Information [Line Items]
Net interest income (expense)	738	659	1,429	1,208
Provision (benefit) for credit losses	55	5	83	15
Net interest income after provision for credit losses	683	654	1,346	1,193
Noninterest income	152	135	297	253
Noninterest expense	497	469	1,017	867
Income before income taxes	338	320	626	579
Income tax expense (benefit)	93	77	171	137
Net income	245	243	455	442
Loans and leases	65,195	59,651	65,195	59,651
Operating lease equipment, net	0	0	0	0
Deposits	71,479	69,863	71,479	69,863
Operating Segments | Commercial Bank
Segment Reporting Information [Line Items]
Net interest income (expense)	279	258	549	496
Provision (benefit) for credit losses	22	169	36	222
Net interest income after provision for credit losses	257	89	513	274
Noninterest income	131	137	267	280
Noninterest expense	221	199	449	409
Income before income taxes	167	27	331	145
Income tax expense (benefit)	44	11	86	41
Net income	123	16	245	104
Loans and leases	32,116	29,170	32,116	29,170
Operating lease equipment, net	767	741	767	741
Deposits	2,958	3,067	2,958	3,067
Operating Segments | SVB Commercial
Segment Reporting Information [Line Items]
Net interest income (expense)	577	554	1,123	591
Provision (benefit) for credit losses	18	(22)	40	(22)
Net interest income after provision for credit losses	559	576	1,083	613
Noninterest income	139	145	276	154
Noninterest expense	387	464	771	487
Income before income taxes	311	257	588	280
Income tax expense (benefit)	85	70	160	75
Net income	226	187	428	205
Loans and leases	41,968	44,130	41,968	44,130
Operating lease equipment, net	0	0	0	0
Deposits	35,891	37,092	35,891	37,092
Operating Segments | Rail
Segment Reporting Information [Line Items]
Net interest income (expense)	(45)	(33)	(88)	(61)
Provision (benefit) for credit losses	0	0	0	0
Net interest income after provision for credit losses	(45)	(33)	(88)	(61)
Noninterest income	203	178	405	355
Noninterest expense	129	121	244	241
Income before income taxes	29	24	73	53
Income tax expense (benefit)	8	6	19	13
Net income	21	18	54	40
Loans and leases	62	64	62	64
Operating lease equipment, net	8,178	7,790	8,178	7,790
Deposits	10	11	10	11
Corporate
Segment Reporting Information [Line Items]
Net interest income (expense)	272	523	625	577
Provision (benefit) for credit losses	0	(1)	0	719
Net interest income after provision for credit losses	272	524	625	(142)
Noninterest income	14	63	21	9,875
Noninterest expense	152	319	281	423
Income before income taxes	134	268	365	9,310
Income tax expense (benefit)	42	50	109	(99)
Net income	92	218	256	9,409
Loans and leases	0	0	0	0
Operating lease equipment, net	0	0	0	0
Deposits	$ 40,741	$ 31,131	$ 40,741	$ 31,131