Segment Reporting - Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Net interest income	$ 852	$ 528	$ 2,240	$ 1,565
(Provision for) reduction of credit losses	(21)	52	(75)	(258)
Noninterest income	672	547	2,177	1,218
Noninterest expense	(879)	(491)	(2,168)	(1,370)
Income before income tax expense	624	636	2,174	1,155
Total average loans, amortized cost	59,291	37,319	51,843	35,836
Total average assets	182,690	88,348	152,952	79,761
Total average deposits	163,392	77,680	136,113	69,166
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income	182	148	515	448
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income	25	1	27	2
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income	145	60	389	87
SVB Leerink
Segment Reporting Information [Line Items]
Noninterest income	131	114	450	340
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income	774	513	2,108	1,462
(Provision for) reduction of credit losses	29	38	(27)	(200)
Noninterest income	182	148	515	448
Noninterest expense	(339)	(258)	(919)	(725)
Income before income tax expense	646	441	1,677	985
Total average loans, amortized cost	45,798	30,764	42,628	30,127
Total average assets	152,364	77,803	131,218	69,213
Total average deposits	149,160	74,826	128,272	66,408
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income	66	19	122	53
(Provision for) reduction of credit losses	(20)	15	(16)	(44)
Noninterest income	25	1	27	2
Noninterest expense	(90)	(12)	(118)	(33)
Income before income tax expense	(19)	23	15	(22)
Total average loans, amortized cost	12,506	4,263	7,573	4,053
Total average assets	14,918	4,297	8,418	4,088
Total average deposits	13,150	2,164	6,842	2,069
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income	0	0	0	0
(Provision for) reduction of credit losses	0	0	0	0
Noninterest income	145	60	389	87
Noninterest expense	(15)	(11)	(48)	(28)
Income before income tax expense	130	49	341	59
Total average loans, amortized cost	0	0	0	0
Total average assets	730	414	641	430
Total average deposits	0	0	0	0
Operating segments | SVB Leerink
Segment Reporting Information [Line Items]
Net interest income	0	0	0	0
(Provision for) reduction of credit losses	0	0	0	0
Noninterest income	131	114	450	340
Noninterest expense	(142)	(78)	(376)	(248)
Income before income tax expense	(11)	36	74	92
Total average loans, amortized cost	0	0	0	0
Total average assets	837	605	778	515
Total average deposits	0	0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income	12	(4)	10	50
(Provision for) reduction of credit losses	(30)	(1)	(32)	(14)
Noninterest income	189	224	796	341
Noninterest expense	(293)	(132)	(707)	(336)
Income before income tax expense	(122)	87	67	41
Total average loans, amortized cost	987	2,292	1,642	1,656
Total average assets	13,841	5,229	11,897	5,515
Total average deposits	$ 1,082	$ 690	$ 999	$ 689