Condensed Statement of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Interest income	$ 147,802	$ 143,324	$ 140,161	$ 134,101	$ 118,709	$ 116,758	$ 116,245	$ 110,019	$ 565,388	$ 461,731	$ 431,226
Interest expense	(7,732)	(7,869)	(9,708)	(13,802)	(14,191)	(10,417)	(9,809)	(9,179)	(39,111)	(43,596)	(49,076)
Gains (losses) on derivative instruments, net									38,681	9,522	(753)
Gains (losses) on investment securities, net									195,034	93,360	(31,209)
Income tax benefit	(26,284)	(26,770)	(43,263)	(22,770)	(11,005)	(24,996)	(13,819)	(11,582)	(119,087)	(61,402)	(35,207)
Net income attributable to SVBFG									171,902	94,951	48,010
Preferred stock dividend and discount accretion											(25,336)
Net income available to common stockholders	35,574	37,571	65,750	33,007	17,487	37,787	21,120	18,557	171,902	94,951	22,674
Parent Company
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Interest income									2,819	1,603	3,179
Interest expense									(27,252)	(22,816)	(17,679)
Gains (losses) on derivative instruments, net									34,654	6,570	(200)
Gains (losses) on investment securities, net									16,432	6,923	(1,319)
General and administrative expenses									(71,355)	(66,489)	(65,400)
Income tax benefit									7,468	24,918	30,398
Loss before net income of subsidiaries									(37,234)	(49,291)	(51,021)
Net income attributable to SVBFG									171,902	94,951	48,010
Preferred stock dividend and discount accretion											(25,336)
Net income available to common stockholders									171,902	94,951	22,674
Parent Company | Nonbank Subsidiaries
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Equity in undistributed net income of subsidiary									22,081	17,536	1,261
Parent Company | Bank Subsidiaries
Schedule of Condensed Consolidating Statement of Operations [Line Items]
Equity in undistributed net income of subsidiary									$ 187,055	$ 126,706	$ 97,770