Segment Reporting - Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Net interest income		$ 342,696	$ 283,336	$ 652,689	$ 564,757
Provision for credit losses		(15,185)	(36,333)	(44,864)	(69,674)
Provision for credit losses	[1]	15,806	36,746	46,540	70,221
Noninterest income		128,528	112,776	246,187	198,910
Noninterest expense	[1]	(251,246)	(199,939)	(488,879)	(403,838)
Income before income tax expense		204,172	159,427	363,457	289,608
Total average loans, net of unearned income		20,508,541	18,199,259	20,290,141	17,605,847
Total average assets		47,549,364	43,370,030	46,431,410	43,780,110
Total average deposits		42,138,646	38,159,959	41,054,613	38,714,044
Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income		311,051	254,680	586,929	510,858
Provision for credit losses		(14,856)	(36,454)	(43,745)	(69,169)
Noninterest income		83,904	77,310	163,423	152,069
Noninterest expense		(175,963)	(147,960)	(348,337)	(302,747)
Income before income tax expense		204,136	147,576	358,270	291,011
Total average loans, net of unearned income		17,907,635	16,026,605	17,778,065	15,473,170
Total average assets		45,483,372	40,703,091	44,193,023	41,118,263
Total average deposits		40,477,823	36,690,002	39,393,219	37,263,823
SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income		14,742	13,538	28,352	27,210
Provision for credit losses		(329)	121	(1,119)	(505)
Noninterest income		536	762	1,254	1,389
Noninterest expense		(4,050)	(2,954)	(7,968)	(6,359)
Income before income tax expense		10,899	11,467	20,519	21,735
Total average loans, net of unearned income		2,365,464	1,986,659	2,305,723	1,929,239
Total average assets		2,397,188	2,007,009	2,335,350	1,933,123
Total average deposits		1,302,890	1,115,599	1,319,776	1,123,167
SVB Capital
Segment Reporting Information [Line Items]
Net interest income		16	(52)	16	(52)
Provision for credit losses		0	0	0	0
Noninterest income		15,019	11,420	31,794	13,873
Noninterest expense		(6,192)	(3,684)	(9,664)	(7,597)
Income before income tax expense		8,843	7,684	22,146	6,224
Total average loans, net of unearned income		0	0	0	0
Total average assets		355,292	331,500	364,036	340,256
Total average deposits		0	0	0	0
Other Items
Segment Reporting Information [Line Items]
Net interest income		16,887	15,170	37,392	26,741
Provision for credit losses		(621)	(413)	(1,676)	(547)
Noninterest income		29,069	23,284	49,716	31,579
Noninterest expense		(65,041)	(45,341)	(122,910)	(87,135)
Income before income tax expense		(19,706)	(7,300)	(37,478)	(29,362)
Total average loans, net of unearned income		235,442	185,995	206,353	203,438
Total average assets		(686,488)	328,430	(460,999)	388,468
Total average deposits		$ 357,933	$ 354,358	$ 341,618	$ 327,054

[1] Our consolidated statements of income for the three and six months ended June 30, 2016 were modified from prior period's presentation to conform to the current period's presentation, which reflects our provision for loan losses and provision for unfunded credit commitments together as our “provision for credit losses”. In prior periods, our provision for unfunded credit commitments were reported as a component of noninterest expense.