Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 520,644	$ 493,222	$ 1,562,933	$ 1,379,528
Provision for credit losses	(36,536)	(17,174)	(89,033)	(74,226)
Noninterest income	294,009	210,070	908,135	558,277
Noninterest expense	(391,324)	(309,445)	(1,140,510)	(880,601)
Income before income tax expense	386,793	376,673	1,241,525	982,978
Total average loans, net of unearned income	29,822,426	26,331,377	29,210,960	25,008,277
Total average assets	65,327,748	56,465,037	61,214,132	54,432,652
Total average deposits	57,234,969	49,092,240	53,331,344	47,734,362
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income	161,029	135,228	471,492	377,320
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income	634	605	1,829	1,677
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income	34,955	24,423	99,860	81,832
SVB Leerink
Segment Reporting Information [Line Items]
Noninterest income	52,947		188,064
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income	455,161	431,036	1,360,997	1,209,960
Provision for credit losses	(34,075)	(19,074)	(79,175)	(71,704)
Noninterest income	161,029	135,228	471,492	377,320
Noninterest expense	(213,786)	(206,487)	(617,933)	(591,434)
Income before income tax expense	368,329	340,703	1,135,381	924,142
Total average loans, net of unearned income	25,839,647	22,925,909	25,457,997	21,781,557
Total average assets	58,384,473	49,948,578	54,196,976	48,380,180
Total average deposits	55,250,154	47,037,693	51,352,644	45,701,317
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income	12,772	14,919	37,200	46,811
Provision for credit losses	(1,910)	(362)	(1,779)	(2,384)
Noninterest income	634	605	1,829	1,677
Noninterest expense	(11,638)	(6,760)	(30,015)	(18,729)
Income before income tax expense	(142)	8,402	7,235	27,375
Total average loans, net of unearned income	3,400,889	2,928,576	3,235,943	2,791,910
Total average assets	3,431,313	2,949,908	3,264,071	2,813,101
Total average deposits	1,497,303	1,505,746	1,461,170	1,519,200
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income	9	6	20	22
Provision for credit losses	0	0	0	0
Noninterest income	34,955	24,423	99,860	81,832
Noninterest expense	(8,129)	(6,469)	(21,794)	(17,182)
Income before income tax expense	26,835	17,960	78,086	64,672
Total average loans, net of unearned income	0	0	0	0
Total average assets	396,031	388,531	382,707	379,809
Total average deposits	0	0	0	0
Operating segments | SVB Leerink
Segment Reporting Information [Line Items]
Net interest income	277	0	961	0
Provision for credit losses	0	0	0	0
Noninterest income	52,947	0	188,064	0
Noninterest expense	(55,200)	0	(177,675)	0
Income before income tax expense	(1,976)	0	11,350	0
Total average loans, net of unearned income	0	0	0	0
Total average assets	428,848	0	380,290	0
Total average deposits	0	0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income	52,425	47,261	163,755	122,735
Provision for credit losses	(551)	2,262	(8,079)	(138)
Noninterest income	44,444	49,814	146,890	97,448
Noninterest expense	(102,571)	(89,729)	(293,093)	(253,256)
Income before income tax expense	(6,253)	9,608	9,473	(33,211)
Total average loans, net of unearned income	581,890	476,892	517,020	434,810
Total average assets	2,687,083	3,178,020	2,990,088	2,859,562
Total average deposits	$ 487,512	$ 548,801	$ 517,530	$ 513,845