Major Components of Investment Securities Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Investment Holdings [Line Items]
Amortized Cost	$ 10,384,741		$ 7,877,842
Unrealized Gains	157,105		60,593
Unrealized Losses	(5,800)		(20,468)
Carrying Value	10,536,046		7,917,967
Non-marketable securities	1,004,440		721,520
Investment securities	11,540,486		8,639,487
Agency-issued commercial mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost	176,646
Unrealized Gains	2,047
Carrying Value	178,693
Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	611,824	[1]	391,247	[1]
Fair value accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	987	[2]	981	[2]
Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	124,121	[3]	111,843	[3]
Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	68,252	[4]	67,031	[4]
Equity method accounting | Low income housing tax credit funds
Investment Holdings [Line Items]
Non-marketable securities	34,894		27,832
Cost method accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	145,007	[5]	110,466	[5]
Cost method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	19,355		12,120
U.S. treasury securities
Investment Holdings [Line Items]
Amortized Cost	25,233		25,408
Unrealized Gains	731		1,002
Carrying Value	25,964		26,410
U.S. agency debentures
Investment Holdings [Line Items]
Amortized Cost	2,822,158		2,844,973
Unrealized Gains	52,864		7,077
Unrealized Losses	(90)		(16,957)
Carrying Value	2,874,932		2,835,093
Residential mortgage-backed securities | Agency-issued commercial mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost	1,529,466		1,234,120
Unrealized Gains	34,926		15,487
Unrealized Losses	(106)		(1,097)
Carrying Value	1,564,286		1,248,510
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Investment Holdings [Line Items]
Amortized Cost	3,317,285		806,032
Unrealized Gains	56,546		24,435
Unrealized Losses	(71)		(1)
Carrying Value	3,373,760		830,466
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Investment Holdings [Line Items]
Amortized Cost	2,416,158		2,870,570
Unrealized Gains	1,554		10,394
Unrealized Losses	(4,334)		(1,439)
Carrying Value	2,413,378		2,879,525
Municipal bonds and notes
Investment Holdings [Line Items]
Amortized Cost	92,241		96,381
Unrealized Gains	8,257		2,164
Unrealized Losses			(965)
Carrying Value	100,498		97,580
Equity securities
Investment Holdings [Line Items]
Amortized Cost	5,554		358
Unrealized Gains	180		34
Unrealized Losses	(1,199)		(9)
Carrying Value	$ 4,535		$ 383

[1] The following table shows the amount of venture capital and private equity fund investments by the following consolidated funds and our ownership of each fund at December 31, 2011 and 2010: December 31, 2011 December 31, 2010 (Dollars in thousands) Amount Ownership % Amount Ownership % SVB Strategic Investors Fund, LP $ 39,567 12.6 % $ 44,722 12.6 % SVB Strategic Investors Fund II, LP 122,619 8.6 94,694 8.6 SVB Strategic Investors Fund III, LP 218,429 5.9 146,613 5.9 SVB Strategic Investors Fund IV, LP 122,076 5.0 40,639 5.0 Strategic Investors Fund V, LP 8,838 0.3 - - SVB Capital Preferred Return Fund, LP 42,580 20.0 23,071 20.0 SVB Capital-NT Growth Partners, LP 43,958 33.0 28,624 33.0 SVB Capital Partners II, LP (i) 2,390 5.1 4,506 5.1 Other private equity fund (ii) 11,367 58.2 8,378 60.6 Total venture capital and private equity fund investments $ 611,824 $ 391,247 (i) At December 31, 2011, we had a direct ownership interest of 1.3 percent and an indirect ownership interest of 3.8 percent in the fund through our ownership of SVB Strategic Investors Fund II, LP. (ii) At December 31, 2011, we had a direct ownership interest of 41.5 percent and an indirect ownership interest of 12.6 percent and 4.1 percent in the fund through our ownership interests of SVB Capital-NT Growth Partners, LP and SVB Capital Preferred Return Fund, LP, respectively.

[2] Other investments within non-marketable securities (fair value accounting) include our ownership in Partners for Growth, LP, a consolidated debt fund. At December 31, 2011 we had a majority ownership interest of slightly more than 50.0 % in the fund. Partners for Growth, LP is managed by a third party and we do not have an ownership interest in the general partner of this fund.

[3] The following table shows the amount of other venture capital investments by the following consolidated funds and our ownership of each fund at December 31, 2011 and 2010: December 31, 2011 December 31, 2010 (Dollars in thousands) Amount Ownership % Amount Ownership % Silicon Valley BancVentures, LP $ 17,878 10.7 % $ 21,371 10.7 % SVB Capital Partners II, LP (i) 61,099 5.1 51,545 5.1 SVB India Capital Partners I, LP 42,832 14.4 38,927 14.4 SVB Capital Shanghai Yangpu Venture Capital Fund 2,312 6.8 - - Total other venture capital investments $ 124,121 $ 111,843 (i) At December 31, 2011, we had a direct ownership interest of 1.3 percent and an indirect ownership interest of 3.8 percent in the fund through our ownership of SVB Strategic Investors Fund II, LP.

[4] The following table shows the carrying value and our ownership percentage of each investment at December 31, 2011 and 2010: December 31, 2011 December 31, 2010 (Dollars in thousands) Amount Ownership % Amount Ownership % Gold Hill Venture Lending 03, LP (i) $ 16,072 9.3 % $ 17,826 9.3 % Gold Hill Capital 2008, LP (ii) 19,328 15.5 12,101 15.5 Partners for Growth II, LP 3,785 24.2 10,465 24.2 Other investments 29,067 N/A 26,639 N/A Total other investments $ 68,252 $ 67,031 (i) At December 31, 2011, we had a direct ownership interest of 4.8 percent in the fund and an indirect interest in the fund through our investment in GHLLC of 4.5 percent. Our aggregate direct and indirect ownership in the fund is 9.3 percent. (ii) At December 31, 2011, we had a direct ownership interest of 11.5 percent in the fund and an indirect interest in the fund through our investment in Gold Hill Capital 2008, LLC of 4.0 percent. Our aggregate direct and indirect ownership in the fund is 15.5 percent.

[5] Represents investments in 329 and 343 funds (primarily venture capital funds) at December 31, 2011 and 2010, respectively, where our ownership interest is less than 5% of the voting interests of each such fund and in which we do not have the ability to exercise significant influence over the partnerships operating and financial policies. For the year ended December 31, 2011, we recognized other-than-temporary impairment ("OTTI") losses of $1.0 million resulting from other-than-temporary declines in value for 41 of the 329 investments. The OTTI losses are included in net gains (losses) on investment securities, a component of noninterest income. For the remaining 288 investments at December 31, 2011, we concluded that declines in value, if any, were temporary and as such, no OTTI was required to be recognized. At December 31, 2011, the carrying value of these venture capital and private equity fund investments (cost method accounting) was $145.0 million, and the estimated fair value was $163.7 million.