Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest income	$ 533,668	$ 520,644	$ 529,403	$ 512,886	$ 514,460	$ 493,222	$ 466,443	$ 419,863	$ 2,096,601	$ 1,893,988	$ 1,420,369
Provision for credit losses									(106,416)	(87,870)	(92,304)
Noninterest income	313,344	294,009	333,750	280,376	186,707	210,070	192,689	155,518	1,221,479	744,984	557,231
Noninterest expense	$ (460,752)	$ (391,324)	$ (383,522)	$ (365,664)	$ (307,592)	$ (309,445)	$ (305,739)	$ (265,417)	(1,601,262)	(1,188,193)	(1,010,655)
Income before income tax expense									1,610,402	1,362,909	874,641
Total average loans, net of unearned income									29,916,207	25,630,520	21,159,394
Total average assets									63,211,630	55,229,060	48,380,272
Total average deposits									55,056,950	48,075,344	42,745,148
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income									637,922	520,302
Income before income tax expense									1,521,645	1,269,678
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income									3,366	2,281
Income before income tax expense									11,868	38,780
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income									122,394	101,181
Income before income tax expense									91,634	78,412
SVB Leerink
Segment Reporting Information [Line Items]
Noninterest income									264,516
Income before income tax expense									13,090	0
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income									1,850,391	1,623,488	1,274,366
Provision for credit losses									(91,814)	(80,953)	(81,553)
Noninterest income									637,922	520,302	392,101
Noninterest expense									(874,854)	(793,159)	(707,666)
Income before income tax expense											877,248
Total average loans, net of unearned income									26,031,284	22,354,305	18,479,793
Total average assets									56,043,321	48,854,416	43,704,667
Total average deposits									53,053,665	46,039,570	41,043,731
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income									51,022	64,902	58,131
Provision for credit losses									(2,369)	(3,339)	(4,386)
Noninterest income									3,366	2,281	2,175
Noninterest expense									(40,151)	(25,064)	(17,693)
Income before income tax expense											38,227
Total average loans, net of unearned income									3,341,188	2,850,271	2,423,078
Total average assets									3,371,052	2,871,743	2,445,220
Total average deposits									1,524,232	1,502,308	1,303,542
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income									38	23	48
Provision for credit losses									0	0	0
Noninterest income									122,394	101,181	58,992
Noninterest expense									(30,798)	(22,792)	(19,340)
Income before income tax expense											39,700
Total average loans, net of unearned income									0	0	0
Total average assets									405,152	380,543	325,939
Total average deposits									0	0	0
Operating segments | SVB Leerink
Segment Reporting Information [Line Items]
Net interest income									1,252	0	0
Provision for credit losses									0	0	0
Noninterest income									264,516	0	0
Noninterest expense									(252,678)	0	0
Income before income tax expense											0
Total average loans, net of unearned income									0	0	0
Total average assets									397,650	0	0
Total average deposits									0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income									193,898	205,575	87,824
Provision for credit losses									(12,233)	(3,578)	(6,365)
Noninterest income									193,281	121,220	103,963
Noninterest expense									(402,781)	(347,178)	(265,956)
Income before income tax expense									(27,835)	(23,961)	(80,534)
Total average loans, net of unearned income									543,735	425,944	256,523
Total average assets									2,994,455	3,122,358	1,904,446
Total average deposits									$ 479,053	$ 533,466	$ 397,875