Major Components of Investment Securities Portfolio (Detail) (USD $) In Thousands	Sep. 30, 2011		Dec. 31, 2010
Investment Holdings [Line Items]
Amortized Cost	$ 9,468,094		$ 7,877,842
Unrealized Gains	173,679		60,593
Unrealized Losses	(2,387)		(20,468)
Carrying Value	9,639,386		7,917,967
Non-marketable securities	951,963		721,520
Investment securities	10,591,349		8,639,487
U.S. treasury securities
Investment Holdings [Line Items]
Amortized Cost	25,277		25,408
Unrealized Gains	853		1,002
Carrying Value	26,130		26,410
U.S. agency debentures
Investment Holdings [Line Items]
Amortized Cost	2,896,079		2,844,973
Unrealized Gains	49,460		7,077
Unrealized Losses	(2)		(16,957)
Carrying Value	2,945,537		2,835,093
Residential mortgage-backed securities | Agency-issued mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost	1,461,806		1,234,120
Unrealized Gains	42,205		15,487
Unrealized Losses	(160)		(1,097)
Carrying Value	1,503,851		1,248,510
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Investment Holdings [Line Items]
Amortized Cost	2,332,140		806,032
Unrealized Gains	70,092		24,435
Unrealized Losses			(1)
Carrying Value	2,402,232		830,466
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Investment Holdings [Line Items]
Amortized Cost	2,558,348		2,870,570
Unrealized Gains	2,905		10,394
Unrealized Losses	(2,092)		(1,439)
Carrying Value	2,559,161		2,879,525
Agency-issued commercial mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost	101,553
Unrealized Gains	1,628
Carrying Value	103,181
Municipal bonds and notes
Investment Holdings [Line Items]
Amortized Cost	92,258		96,381
Unrealized Gains	6,523		2,164
Unrealized Losses	(5)		(965)
Carrying Value	98,776		97,580
Equity securities
Investment Holdings [Line Items]
Amortized Cost	633		358
Unrealized Gains	13		34
Unrealized Losses	(128)		(9)
Carrying Value	518		383
Investment company fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	578,126	[1]	391,247	[1]
Investment company fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	120,160	[2]	111,843	[2]
Investment company fair value accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	973	[3]	981	[3]
Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	65,934	[4]	67,031	[4]
Equity method accounting | Low income housing tax credit funds
Investment Holdings [Line Items]
Non-marketable securities	34,446		27,832
Cost method accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	138,960	[5]	110,466	[5]
Cost method accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	$ 13,364		$ 12,120

[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 September 30, 2011 and December 31, 2010: September 30, 2011 December 31, 2010 (Dollars in thousands) Amount Ownership % Amount Ownership % SVB Strategic Investors Fund, LP $ 44,205 12.6 % $ 44,722 12.6 % SVB Strategic Investors Fund II, LP 122,264 8.6 94,694 8.6 SVB Strategic Investors Fund III, LP 205,505 5.9 146,613 5.9 SVB Strategic Investors Fund IV, LP 104,114 5.0 40,639 5.0 Strategic Investors Fund V, LP 1,965 0.3 - - SVB Capital Preferred Return Fund, LP 41,432 20.0 23,071 20.0 SVB Capital-NT Growth Partners, LP 44,837 33.0 28,624 33.0 SVB Capital Partners II, LP (i) 2,324 5.1 4,506 5.1 Other private equity fund (ii) 11,480 58.2 8,378 60.6 Total venture capital and private equity fund investments $ 578,126 $ 391,247 (i) At September 30, 2011, we had a direct ownership interest of 1.3% and an indirect ownership interest of 3.8% in the fund through our ownership interest of SVB Strategic Investors Fund II, LP. (ii) At September 30, 2011, we had a direct ownership interest of 41.5% and indirect ownership interests of 12.6% and 4.1% in the fund through our ownership interests 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 September 30, 2011 and December 31, 2010: September 30, 2011 December 31, 2010 (Dollars in thousands) Amount Ownership % Amount Ownership % Silicon Valley BancVentures, LP $ 16,606 10.7 % $ 21,371 10.7 % SVB Capital Partners II, LP (i) 60,129 5.1 51,545 5.1 SVB India Capital Partners I, LP 41,927 14.4 38,927 14.4 SVB Capital Shanghai Yangpu Venture Capital Fund 1,498 6.8 - - Total other venture capital investments $ 120,160 $ 111,843 (i) At September 30, 2011, we had a direct ownership interest of 1.3% and an indirect ownership interest of 3.8% in the fund through our ownership of SVB Strategic Investors Fund II, LP.

[3] Other investments within non-marketable securities (investment company fair value accounting) include our ownership in Partners for Growth, LP, a consolidated debt fund. At both September 30, 2011 and December 31, 2010, 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.

[4] The following table shows the carrying value and our ownership percentage of each investment at September 30, 2011 and December 31, 2010: September 30, 2011 December 31, 2010 (Dollars in thousands) Amount Ownership % Amount Ownership % Gold Hill Venture Lending 03, LP (i) $ 16,781 9.3 % $ 17,826 9.3 % Gold Hill Capital 2008, LP (ii) 16,414 15.5 12,101 15.5 Partners for Growth II, LP 3,564 24.2 10,465 24.2 Other investments 29,175 N/A 26,639 N/A Total other investments $ 65,934 $ 67,031 (i) At September 30, 2011, we had a direct ownership interest of 4.8% 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%. Our aggregate direct and indirect ownership in the fund is 9.3%. (ii) At September 30, 2011, we had a direct ownership interest of 11.5% in the fund and an indirect interest in the fund through our investment in Gold Hill Capital 2008, LLC of 4.0%. Our aggregate direct and indirect ownership in the fund is 15.5%.

[5] Represents investments in 329 and 343 funds (primarily venture capital funds) at September 30, 2011 and December 31, 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 three months ended September 30, 2011, we recognized other-than-temporary impairment ("OTTI") losses of $0 million resulting from other-than-temporary declines in value for 0 of the 0 investments. For the nine months ended September 30, 2011, we recognized OTTI losses of $0 million resulting from other-than-temporary declines in value for 0 of the 0 investments. The OTTI losses are included in net gains on investment securities, a component of noninterest income. For the remaining 0 investments at September 30, 2011, we concluded that declines in value, if any, were temporary and as such, no OTTI was required to be recognized. At September 30, 2011, the carrying value of these venture capital and private equity fund investments (cost method accounting) was $0 million, and the estimated fair value was $0 million.