Segment Reporting - Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Segment Reporting Information [Line Items]
Net interest income		$ 243,771	$ 204,965	$ 482,696	[1]	$ 401,293
Provision for loan losses		(26,513)	(1,947)	(32,965)	[1]	(2,441)
Noninterest income		126,287	14,210	249,811	[1]	324,435
Noninterest expense	[2]	(194,112)	(170,944)	(384,653)	[1]	(341,352)
Income before income tax expense	[2]	149,433	46,284	314,889	[1]	381,935
Total average loans, net of unearned income		14,320,875	11,080,602	14,185,333		10,925,007
Total average assets		39,448,023	31,745,630	38,840,208		29,767,621
Total average deposits		34,956,067	27,177,125	34,412,173		25,436,457
Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income		203,945	178,046	407,753		353,349
Provision for loan losses		(25,592)	(1,841)	(32,052)		(2,648)
Noninterest income		66,031	53,027	130,720		111,662
Noninterest expense		(143,459)	(121,827)	(279,741)		(242,533)
Income before income tax expense		100,925	107,405	226,680		219,830
Total average loans, net of unearned income		12,824,661	9,874,780	12,777,409		9,776,913
Total average assets		37,544,170	29,214,978	36,813,121		27,403,905
Total average deposits		33,714,023	26,323,795	33,096,854		24,610,326
SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income		11,109	9,293	20,832		16,185
Provision for loan losses		(921)	(106)	(913)		207
Noninterest income		595	356	992		630
Noninterest expense		(3,139)	(2,640)	(5,886)		(5,135)
Income before income tax expense		7,644	6,903	15,025		11,887
Total average loans, net of unearned income		1,542,046	1,119,503	1,458,581		1,084,894
Total average assets		2,216,622	986,392	2,069,903		975,740
Total average deposits		1,084,632	791,261	1,167,823		768,300
SVB Capital
Segment Reporting Information [Line Items]
Net interest income		1	29	2		43
Provision for loan losses		0	0	0		0
Noninterest income		19,909	(3,119)	40,587		34,553
Noninterest expense		(3,704)	(3,144)	(7,190)		(5,779)
Income before income tax expense		16,206	(6,234)	33,399		28,817
Total average loans, net of unearned income		0	0	0		0
Total average assets		330,016	342,924	335,690		342,451
Total average deposits		0	0	0		0
Other Items
Segment Reporting Information [Line Items]
Net interest income		28,716	17,597	54,109		31,716
Provision for loan losses		0	0	0		0
Noninterest income		39,752	(36,054)	77,512		177,590
Noninterest expense		(43,810)	(43,333)	(91,836)		(87,905)
Income before income tax expense		24,658	(61,790)	39,785		121,401
Total average loans, net of unearned income		(45,832)	86,319	(50,657)		63,200
Total average assets		(642,785)	1,201,336	(378,506)		1,045,525
Total average deposits		$ 157,412	$ 62,069	$ 147,496		$ 57,831

[1] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjA2NWJiNjIxZjM0ZjRmOWVhYzRkYjZjMWUyZjAzZTk2fFRleHRTZWxlY3Rpb246ODVBMjJCNzk0NDdCOEEwRjQ3QTIwMTA2RUZDRUFERDEM}

[2] Prior period amounts have been revised to reflect the retrospective application of new accounting guidance adopted in the first quarter of 2015 related to our investments in qualified affordable housing projects (ASU 2014-01). See Note 1— "Basis of Presentation" of the "Notes to Interim Consolidated Financial Statements" under Part I, Item 1 in this report.