Investment Securities - Non-marketable and Other Securities (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014 Investment
Investment Holdings [Line Items]
Total non-marketable and other securities	$ 1,706,873		$ 1,728,140	[1]
Ownership interest percentage			5.00%
Low Income Housing Tax Credit Funds [Member]
Investment Holdings [Line Items]
Nonmarketable Securities Other	125,357	[1]	121,155	[1]
Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities	11,936	[2]	108,251	[2]
Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	78,850	[3]	71,204	[3]
Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	1,195,303	[4]	1,130,882	[4]
Non-marketable securities	238,000		234,000
Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	145,942	[5]	142,674	[5]
Cost method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	14,910	[1]	13,423	[1]
Cost method accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	134,575	[6]	140,551	[6]
Number of investments	277		281		282
Upper Limit
Investment Holdings [Line Items]
Ownership interest percentage	5.00%
SVB Strategic Investors Fund, LP | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	23,953		24,645
Percentage of ownership	12.60%		12.60%
SVB Strategic Investors Fund II, LP | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	89,219		97,250
Percentage of ownership	8.60%		8.60%
SVB Strategic Investors Fund III, LP | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	257,539		269,821
Percentage of ownership	5.90%		5.90%
SVB Strategic Investors Fund IV, LP | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	297,752		291,291
Percentage of ownership	5.00%		5.00%
Strategic Investors Fund V Funds | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	260,292		226,111
Strategic Investors Fund VI Funds | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	127,721		89,605
Percentage of ownership	0.00%		0.00%
Strategic Investors Fund VII Funds [Domain] | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	2,212		0
Percentage of ownership	0.00%		0.00%
SVB Capital Preferred Return Fund, LP | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	64,417		62,110
Percentage of ownership	20.00%		20.00%
SVB Capital—NT Growth Partners, LP | Venture capital and private equity fund investments | Indirect ownership interest | Other investments
Investment Holdings [Line Items]
Percentage of ownership	12.60%
SVB Capital—NT Growth Partners, LP | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	64,078		61,973
Percentage of ownership	33.00%		33.00%
SVB Capital Partners II, LP | Venture capital and private equity fund investments | Direct ownership interest | Other investments
Investment Holdings [Line Items]
Percentage of ownership	1.30%
SVB Capital Partners II, LP | Venture capital and private equity fund investments | Indirect ownership interest | Other investments
Investment Holdings [Line Items]
Percentage of ownership	3.80%
SVB Capital Partners II, LP | Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	27,215	[7]	20,481	[7]
Percentage of ownership	5.10%	[7]	5.10%	[7]
SVB Capital Partners II, LP | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	346	[8]	302	[8]
Percentage of ownership	5.10%	[8]	5.10%	[8]
SVB Capital Partners II, LP | Fair value accounting | Direct ownership interest | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Percentage of ownership	1.30%
SVB Capital Partners II, LP | Fair value accounting | Indirect ownership interest | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Percentage of ownership	3.80%
Other private equity fund | Venture capital and private equity fund investments | Direct ownership interest | Other investments
Investment Holdings [Line Items]
Percentage of ownership	41.50%
Other private equity fund | Fair value accounting | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities	7,774	[9]	7,774	[9]
Percentage of ownership	58.20%	[9]	58.20%	[9]
Other private equity fund | Fair value accounting | Direct ownership interest | Venture capital and private equity fund investments
Investment Holdings [Line Items]
Percentage of ownership	41.50%
Silicon Valley BancVentures, LP | Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	3,390		3,291
Percentage of ownership	10.70%		10.70%
Capital Partners III, LP | Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	41,055		41,055
Percentage of ownership	0.00%		0.00%
SVB Capital Shanghai Yangpu Venture Capital Fund | Fair value accounting | Other venture capital investments
Investment Holdings [Line Items]
Non-marketable securities	7,190		6,377
Percentage of ownership	6.80%		6.80%
Gold Hill Capital 2008, LP | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	22,040	[10]	21,294	[10]
Percentage of ownership	15.50%	[10]	15.50%	[10]
Gold Hill Capital 2008, LP | Equity method accounting | Direct ownership interest | Other investments
Investment Holdings [Line Items]
Percentage of ownership	11.50%
Gold Hill Capital 2008, LP | Equity method accounting | Indirect ownership interest | Other investments
Investment Holdings [Line Items]
Percentage of ownership	4.00%
China Joint Venture investment | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	79,695		79,569
Percentage of ownership	50.00%		50.00%
Other investments | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities	$ 44,207		$ 41,811
LP and SVB Capital Preferred Return Fund, LP | Venture capital and private equity fund investments | Indirect ownership interest | Other investments
Investment Holdings [Line Items]
Percentage of ownership	4.10%

[1] Prior period amounts have been revised to reflect the retrospective application of new accounting guidance adopted in the first quarter of 2015 related to our investments in qualified affordable housing projects (ASU 2014-01). See Note 1 - "Basis of Presentation" of the "Notes to Interim Consolidated Financial Statements" under Part I, Item 1 in this report.

[2] Investments classified as other securities (fair value accounting) represent direct equity investments in public companies held by our consolidated funds. At December 31, 2014, the amount primarily included total unrealized gains in one public company, FireEye, Inc. ("FireEye"). During the first quarter of 2015, our managed direct venture funds distributed the remaining 2.5 million shares of FireEye common stock to their respective investors (including the Company), resulting in $15.9 million of realized gains on investment securities ($3.3 million net of noncontrolling interests but inclusive of the Company's carried interests). As of March 31, 2015, we no longer hold any shares of FireEye common stock, either directly or through our managed direct venture funds.

[3] 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, 2015 and December 31, 2014 (fair value accounting): March 31, 2015 December 31, 2014(Dollars in thousands) Amount Ownership % Amount Ownership %Silicon Valley BancVentures, LP $3,390 10.7% $3,291 10.7%SVB Capital Partners II, LP (i) 27,215 5.1 20,481 5.1Capital Partners III, LP 41,055 — 41,055 —SVB Capital Shanghai Yangpu Venture Capital Fund 7,190 6.8 6,377 6.8Total other venture capital investments $78,850 $71,204 (i)At March 31, 2015, 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 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, 2015 and December 31, 2014 (fair value accounting): March 31, 2015 December 31, 2014(Dollars in thousands) Amount Ownership % Amount Ownership %SVB Strategic Investors Fund, LP $23,953 12.6% $24,645 12.6%SVB Strategic Investors Fund II, LP 89,219 8.6 97,250 8.6SVB Strategic Investors Fund III, LP 257,539 5.9 269,821 5.9SVB Strategic Investors Fund IV, LP 297,752 5.0 291,291 5.0Strategic Investors Fund V Funds 260,292 Various 226,111 VariousStrategic Investors Fund VI Funds 127,721 — 89,605 —Strategic Investors Fund VII Funds 2,212 — — —SVB Capital Preferred Return Fund, LP 64,417 20.0 62,110 20.0SVB Capital—NT Growth Partners, LP 64,078 33.0 61,973 33.0SVB Capital Partners II, LP (i) 346 5.1 302 5.1Other private equity fund (ii) 7,774 58.2 7,774 58.2Total venture capital and private equity fund investments $1,195,303 $1,130,882 (i)At March 31, 2015, 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, 2015, 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.

[5] The following table shows the carrying value and our ownership percentage of each investment at March 31, 2015 and December 31, 2014 (equity method accounting): March 31, 2015 December 31, 2014(Dollars in thousands) Amount Ownership % Amount Ownership %Gold Hill Capital 2008, LP (i) $22,040 15.5% $21,294 15.5%China Joint Venture investment 79,695 50.0 79,569 50.0Other investments 44,207 Various 41,811 VariousTotal other investments (equity method accounting) $145,942 $142,674 (i)At March 31, 2015, 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.

[6] Represents investments in 277 and 281 funds (primarily venture capital funds) at March 31, 2015 and December 31, 2014, respectively, where our ownership interest is typically 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. The carrying value, and estimated fair value, of these venture capital and private equity fund investments (cost method accounting) was $135 million, and $238 million, respectively, as of March 31, 2015. The carrying value, and estimated fair value, of these venture capital and private equity fund investments (cost method accounting) was $141 million and $234 million, respectively, as of December 31, 2014.

[7] At March 31, 2015, 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.

[8] At March 31, 2015, 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.

[9] At March 31, 2015, 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.

[10] At March 31, 2015, 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.