Investment Securities - Major Components of Investment Securities Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Investment Holdings [Line Items]
Amortized Cost	$ 10,739,192		$ 11,152,150
Unrealized Gains	173,669		192,960
Unrealized Losses	(4,698)		(1,933)
Available-for-sale securities	10,908,163		11,343,177
Non-marketable securities	1,215,788		1,184,265
Total investment securities	12,123,951		12,527,442
Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	701,076	[1]	665,921	[1]
Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	124,786	[2]	127,091	[2]
Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	140,607	[3]	139,330	[3]
Equity method accounting | Low income housing tax credit funds
Investment Holdings [Line Items]
Non-marketable securities	69,263		70,318
Cost method accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	160,870	[4]	161,884	[4]
Cost method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	19,186		19,721
U.S. treasury securities
Investment Holdings [Line Items]
Amortized Cost	99,993		25,057
Unrealized Gains	53		190
Unrealized Losses	0		0
Available-for-sale securities	100,046		25,247
U.S. agency debentures
Investment Holdings [Line Items]
Amortized Cost	3,415,170		3,370,455
Unrealized Gains	69,116		77,173
Unrealized Losses	(383)		0
Available-for-sale securities	3,483,903		3,447,628
Residential mortgage-backed securities | Agency-issued mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost	1,308,099		1,428,682
Unrealized Gains	40,177		44,858
Unrealized Losses	(446)		(107)
Available-for-sale securities	1,347,830		1,473,433
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Investment Holdings [Line Items]
Amortized Cost	3,818,389		4,063,020
Unrealized Gains	38,200		41,949
Unrealized Losses	(1,522)		(995)
Available-for-sale securities	3,855,067		4,103,974
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Investment Holdings [Line Items]
Amortized Cost	1,593,456		1,760,551
Unrealized Gains	9,425		12,201
Unrealized Losses	(28)		(4)
Available-for-sale securities	1,602,853		1,772,748
Agency-issued commercial mortgage-backed securities
Investment Holdings [Line Items]
Amortized Cost	414,300		416,487
Unrealized Gains	6,275		6,100
Unrealized Losses	(1,240)		(489)
Available-for-sale securities	419,335		422,098
Municipal bonds and notes
Investment Holdings [Line Items]
Amortized Cost	83,299		85,790
Unrealized Gains	7,204		7,750
Unrealized Losses	0		(11)
Available-for-sale securities	90,503		93,529
Equity securities
Investment Holdings [Line Items]
Amortized Cost	6,486		2,108
Unrealized Gains	3,219		2,739
Unrealized Losses	(1,079)		(327)
Available-for-sale securities	$ 8,626		$ 4,520

[1] The following table shows the amounts of venture capital and private equity fund investments held by the following consolidated funds and our ownership percentage of each fund at March 31, 2013 and December 31, 2012 (fair value accounting): March 31, 2013 December 31, 2012(Dollars in thousands) Amount Ownership % Amount Ownership %SVB Strategic Investors Fund, LP $32,142 12.6% $32,850 12.6%SVB Strategic Investors Fund II, LP 92,834 8.6 91,294 8.6SVB Strategic Investors Fund III, LP 212,392 5.9 209,696 5.9SVB Strategic Investors Fund IV, LP 189,369 5.0 169,931 5.0Strategic Investors Fund V Funds 51,985 Various 40,622 VariousSVB Capital Preferred Return Fund, LP 54,919 20.0 53,643 20.0SVB Capital—NT Growth Partners, LP 59,835 33.0 60,120 33.0SVB Capital Partners II, LP (i) 1,138 5.1 1,303 5.1Other private equity fund (ii) 6,462 58.2 6,462 58.2Total venture capital and private equity fund investments $701,076 $665,921 (i)At March 31, 2013, 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 March 31, 2013, 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 amounts of other venture capital investments held by the following consolidated funds and our ownership percentage of each fund at March 31, 2013 and December 31, 2012 (fair value accounting): March 31, 2013 December 31, 2012(Dollars in thousands) Amount Ownership % Amount Ownership %Silicon Valley BancVentures, LP $39,971 10.7% $43,493 10.7%SVB Capital Partners II, LP (i) 80,966 5.1 79,761 5.1SVB Capital Shanghai Yangpu Venture Capital Fund 3,849 6.8 3,837 6.8Total other venture capital investments $124,786 $127,091 (i)At March 31, 2013, 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] The following table shows the carrying value and our ownership percentage of each investment at March 31, 2013 and December 31, 2012 (equity method accounting): March 31, 2013 December 31, 2012(Dollars in thousands) Amount Ownership % Amount Ownership %Gold Hill Venture Lending 03, LP (i) $11,794 9.3% $9,413 9.3%Gold Hill Capital 2008, LP (ii) 20,047 15.5 20,893 15.5China Joint Venture investment 79,210 50.0 78,545 50.0Other investments 29,556 Various 30,479 VariousTotal other investments (equity method accounting) $140,607 $139,330 (i)At March 31, 2013, 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. (ii)At March 31, 2013, 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.

[4] Represents investments in 309 and 324 funds (primarily venture capital funds) at March 31, 2013 and December 31, 2012, 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 activities and financial policies. For the three months ended March 31, 2013, we recognized OTTI losses of $0.5 million resulting from other-than-temporary declines in value for 16 of the 309 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 investments were temporary and as such, no OTTI was required to be recognized. At March 31, 2013, the carrying value of these venture capital and private equity fund investments (cost method accounting) was $161 million, and the estimated fair value was $200 million.