Segment Reporting - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 591,480	$ 527,740	$ 512,927	$ 524,137	$ 533,668	$ 520,644	$ 529,403	$ 512,886	$ 2,156,284	$ 2,096,601	$ 1,893,988
Provision for credit losses									(219,510)	(106,416)	(87,870)
Noninterest income	621,783	547,583	368,848	301,934	313,344	294,009	333,750	280,376	1,840,148	1,221,479	744,984
Noninterest expense	$ (664,799)	$ (491,021)	$ (479,636)	$ (399,585)	$ (460,752)	$ (391,324)	$ (383,522)	$ (365,664)	(2,035,041)	(1,601,262)	(1,188,193)
Income before income tax expense									1,741,881	1,610,402	1,362,909
Total average loans, net of unearned income									37,265,976	29,916,207	25,630,520
Total average assets									85,791,659	63,211,630	55,229,060
Total average deposits									75,015,430	55,056,950	48,075,344
Global Commercial Bank
Segment Reporting Information [Line Items]
Noninterest income									605,733	637,922	520,302
Income before income tax expense									1,444,991	1,521,645
SVB Private Bank
Segment Reporting Information [Line Items]
Noninterest income									3,536	3,366	2,281
Income before income tax expense									13,598	11,868
SVB Capital
Segment Reporting Information [Line Items]
Noninterest income									225,954	122,394	101,181
Income before income tax expense									175,395	91,634
SVB Leerink
Segment Reporting Information [Line Items]
Noninterest income									495,976	264,516
Income before income tax expense									117,584	13,090
Operating segments | Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income									2,025,240	1,850,391	1,623,488
Provision for credit losses									(165,987)	(91,814)	(80,953)
Noninterest income									605,733	637,922	520,302
Noninterest expense									(1,019,995)	(874,854)	(793,159)
Income before income tax expense											1,269,678
Total average loans, net of unearned income									31,218,037	26,031,284	22,354,305
Total average assets									75,034,226	56,043,321	48,854,416
Total average deposits									72,127,148	53,053,665	46,039,570
Operating segments | SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income									77,490	51,022	64,902
Provision for credit losses									(21,329)	(2,369)	(3,339)
Noninterest income									3,536	3,366	2,281
Noninterest expense									(46,099)	(40,151)	(25,064)
Income before income tax expense											38,780
Total average loans, net of unearned income									4,195,804	3,341,188	2,850,271
Total average assets									4,229,818	3,371,052	2,871,743
Total average deposits									2,171,556	1,524,232	1,502,308
Operating segments | SVB Capital
Segment Reporting Information [Line Items]
Net interest income									30	38	23
Provision for credit losses									0	0	0
Noninterest income									225,954	122,394	101,181
Noninterest expense									(50,589)	(30,798)	(22,792)
Income before income tax expense											78,412
Total average loans, net of unearned income									0	0	0
Total average assets									437,132	405,152	380,543
Total average deposits									0	0	0
Operating segments | SVB Leerink
Segment Reporting Information [Line Items]
Net interest income									578	1,252	0
Provision for credit losses									0	0	0
Noninterest income									495,976	264,516	0
Noninterest expense									(378,970)	(252,678)	0
Income before income tax expense											0
Total average loans, net of unearned income									0	0	0
Total average assets									556,778	397,650	0
Total average deposits									0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income									52,946	193,898	205,575
Provision for credit losses									(32,194)	(12,233)	(3,578)
Noninterest income									508,949	193,281	121,220
Noninterest expense									(539,388)	(402,781)	(347,178)
Income before income tax expense									(9,687)	(27,835)	(23,961)
Total average loans, net of unearned income									1,852,135	543,735	425,944
Total average assets									5,533,705	2,994,455	3,122,358
Total average deposits									$ 716,726	$ 479,053	$ 533,466