Segment Reporting Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Segment Reporting Information [Line Items]
Net interest income		$ 269,069	$ 254,660	$ 243,771	$ 238,925	$ 234,737	$ 220,565	$ 204,965	$ 196,328	$ 1,006,425		$ 856,595		$ 697,344
Provision for loan losses		(31,261)	(33,403)	(26,513)	(6,452)	(40,435)	(16,610)	(1,947)	(494)	(97,629)		(59,486)		(63,693)
Noninterest income		114,506	108,477	126,287	123,524	167,637	80,167	14,210	310,225	472,794		572,239		673,206
Noninterest expense		$ (208,608)	$ (184,755)	$ (194,112)	$ (190,541)	$ (186,067)	$ (179,761)	$ (170,944)	$ (170,408)	(778,016)	[1]	(707,180)	[1]	(615,244)	[1]
Income before income tax expense	[1]									603,574	[2]	662,168		691,613
Total average loans, net of unearned income										14,762,941		11,502,941		9,351,378
Total average assets										40,846,377		32,961,936		23,208,169
Total average deposits										36,293,362		28,320,825		19,619,194
Global Commercial Bank
Segment Reporting Information [Line Items]
Net interest income										853,890		742,274		641,384
Provision for loan losses										(94,915)		(58,622)		(65,290)
Noninterest income										272,862		203,474		202,404
Noninterest expense										(568,685)		(504,606)		(425,230)
Income before income tax expense										463,152		382,520		353,268
Total average loans, net of unearned income										12,973,626		10,129,474		8,287,039
Total average assets										38,813,529		30,306,338		21,411,836
Total average deposits										34,996,888		27,364,246		19,072,608
SVB Private Bank
Segment Reporting Information [Line Items]
Net interest income										44,412		31,427		26,701
Provision for loan losses										(2,714)		(864)		1,597
Noninterest income										2,011		1,494		1,209
Noninterest expense										(11,892)		(10,571)		(9,195)
Income before income tax expense										31,817		21,486		20,312
Total average loans, net of unearned income										1,592,065		1,155,992		919,221
Total average assets										1,433,694		1,149,804		954,831
Total average deposits										1,108,411		890,062		524,398
SVB Capital
Segment Reporting Information [Line Items]
Net interest income										3		58		20
Provision for loan losses										0		0		0
Noninterest income										70,857		58,058		75,037
Noninterest expense										(14,699)		(12,668)		(10,737)
Income before income tax expense										56,161		45,448		64,320
Total average loans, net of unearned income										0		0		0
Total average assets										337,884		320,129		289,328
Total average deposits										0		0		0
Other Items
Segment Reporting Information [Line Items]
Net interest income										108,120		82,836		29,239
Provision for loan losses										0		0		0
Noninterest income										127,064		309,213		394,556
Noninterest expense										(182,740)		(179,335)		(170,082)
Income before income tax expense										52,444		212,714		253,713
Total average loans, net of unearned income										197,250		217,475		145,118
Total average assets										261,270		1,185,665		552,174
Total average deposits										$ 188,063		$ 66,517		$ 22,188

[1] 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 2— "Summary of Significant Accounting Policies” of the “Notes to the Consolidated Financial Statements” under Part II, Item 8 of this report for additional details.

[2] During the second quarter of 2015 we adopted new accounting guidance related to our consolidated variable interest entities (ASU 2015-02). Amounts prior to January 1, 2015 have not been revised for the adoption of this guidance. See Note 2— "Summary of Significant Accounting Policies” of the “Notes to the Consolidated Financial Statements” under Part II, Item 8 of this report for additional details.