Major Components of Investment Securities Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Investment Holdings [Line Items]
Amortized Cost	$ 10,436,454		$ 10,384,741
Unrealized Gains	186,362		157,105
Unrealized Losses	(1,865)		(5,800)
Carrying Value	10,620,951		10,536,046
Non-marketable securities	1,132,312		1,004,440
Investment securities	11,753,263		11,540,486
Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	639,596	[1]	611,824	[1]
Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	120,111	[2]	124,121	[2]
Fair value accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities			987	[3]
Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	138,993	[4]	68,252	[4]
Equity method accounting | Low income housing tax credit funds
Investment Holdings [Line Items]
Non-marketable securities	58,698		34,894
Cost method accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	153,618	[5]	145,007	[5]
Cost method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	21,296		19,355
U.S. treasury securities
Investment Holdings [Line Items]
Amortized Cost	25,146		25,233
Unrealized Gains	453		731
Carrying Value	25,599		25,964
U.S. agency debentures
Investment Holdings [Line Items]
Amortized Cost	2,571,796		2,822,158
Unrealized Gains	68,328		52,864
Unrealized Losses			(90)
Carrying Value	2,640,124		2,874,932
Residential mortgage-backed securities | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Investment Holdings [Line Items]
Amortized Cost	1,668,523		1,529,466
Unrealized Gains	45,276		34,926
Unrealized Losses			(106)
Carrying Value	1,713,799		1,564,286
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Investment Holdings [Line Items]
Amortized Cost	3,751,327		3,317,285
Unrealized Gains	54,283		56,546
Unrealized Losses	(1,399)		(71)
Carrying Value	3,804,211		3,373,760
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Investment Holdings [Line Items]
Amortized Cost	2,103,451		2,416,158
Unrealized Gains	5,081		1,554
Unrealized Losses	(83)		(4,334)
Carrying Value	2,108,449		2,413,378
Agency-issued commercial mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost	223,200		176,646
Unrealized Gains	4,880		2,047
Carrying Value	228,080		178,693
Municipal bonds and notes
Investment Holdings [Line Items]
Amortized Cost	91,659		92,241
Unrealized Gains	8,035		8,257
Carrying Value	99,694		100,498
Equity securities
Investment Holdings [Line Items]
Amortized Cost	1,352		5,554
Unrealized Gains	26		180
Unrealized Losses	(383)		(1,199)
Carrying Value	$ 995		$ 4,535

[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 June 30, 2012 and December 31, 2011: June 30, 2012 December 31, 2011 (Dollars in thousands) Amount Ownership % Amount Ownership % SVB Strategic Investors Fund, LP $ 36,694 12.6 % $ 39,567 12.6 % SVB Strategic Investors Fund II, LP 109,343 8.6 122,619 8.6 SVB Strategic Investors Fund III, LP 213,405 5.9 218,429 5.9 SVB Strategic Investors Fund IV, LP 146,477 5.0 122,076 5.0 Strategic Investors Fund V, LP 18,134 0.2 8,838 0.3 SVB Capital Preferred Return Fund, LP 50,573 20.0 42,580 20.0 SVB Capital-NT Growth Partners, LP 57,588 33.0 43,958 33.0 SVB Capital Partners II, LP (i) 863 5.1 2,390 5.1 Other private equity fund (ii) 6,519 58.2 11,367 58.2 Total venture capital and private equity fund investments $ 639,596 $ 611,824 (i) At June 30, 2012, 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 interest of SVB Strategic Investors Fund II, LP. (ii) At June 30, 2012, we had a direct ownership interest of 41.5 percent and indirect ownership interests of 12.6 percent and 4.1 percent in the fund through our ownership interest of SVB Capital-NT Growth Partners, LP and SVB Capital Preferred Return Fund, LP, respectively.

[2] The following table shows the amount of other venture capital investments by the following consolidated funds and our ownership of each fund at June 30, 2012 and December 31, 2011: June 30, 2012 December 31, 2011 (Dollars in thousands) Amount Ownership % Amount Ownership % Silicon Valley BancVentures, LP $ 16,739 10.7 % $ 17,878 10.7 % SVB Capital Partners II, LP (i) 59,256 5.1 61,099 5.1 SVB India Capital Partners I, LP 40,668 14.4 42,832 14.4 SVB Capital Shanghai Yangpu Venture Capital Fund 3,448 6.8 2,312 6.8 Total other venture capital investments $ 120,111 $ 124,121 (i) At June 30, 2012, 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.

[3] Other investments within non-marketable securities (fair value accounting) include our ownership in Partners for Growth, LP, a consolidated debt fund. At June 30, 2012, we had a majority ownership interest of slightly more than 50.0 percent 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.

[4] The following table shows the carrying value and our ownership percentage of each investment at June 30, 2012 and December 31, 2011: June 30, 2012 December 31, 2011 (Dollars in thousands) Amount Ownership % Amount Ownership % Gold Hill Venture Lending 03, LP (i) $ 6,238 9.3 % $ 16,072 9.3 % Gold Hill Capital 2008, LP (ii) 19,553 15.5 19,328 15.5 Partners for Growth II, LP 3,551 24.2 3,785 24.2 China Joint Venture investment (iii) 79,524 50.0 - - Other investments 30,127 N/A 29,067 N/A Total other investments $ 138,993 $ 68,252 (i) At June 30, 2012, we had a direct ownership interest of 4.8 percent in the fund and an indirect interest in the fund through our investment in Gold Hill Venture Lending Partners 03, LLC ("GHLLC") of 4.5 percent. Our aggregate direct and indirect ownership in the fund is 9.3 percent. (ii) At June 30, 2012, 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. (iii) On May 3, 2012, we contributed $79.7 million to SPD Silicon Valley Bank Co., Ltd., our joint venture bank in China.

[5] Represents investments in 326 and 329 funds (primarily venture capital funds) at June 30, 2012 and December 31, 2011, 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 three months ended June 30, 2012, we recognized OTTI losses of $0.2 million resulting from other-than-temporary declines in value for 12 of the 326 investments. For the six months ended June 30, 2012, we recognized OTTI losses of $0.5 million resulting from other-than-temporary declines in value for 30 of the 326 investments. The OTTI losses are included in net gains on investment securities, a component of noninterest income. We concluded that any declines in value for the remaining 296 investments were temporary and as such, no OTTI was required to be recognized. At June 30, 2012, the carrying value of these venture capital and private equity fund investments (cost method accounting) was $153.6 million, and the estimated fair value was $185.3 million.