Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	$ 13,746,923		$ 13,540,655
Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	4,340		4,609
Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant asset | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	124,456		116,604
Fair value accounting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	11,936	[1]	108,251	[1]
Fair value accounting | Venture capital and private equity fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	1,195,303	[2]	1,130,882	[2]
Fair value accounting | Other venture capital investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	78,850	[3]	71,204	[3]
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	7,914,125		7,302,273
U.S. agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	3,313,664		3,561,556
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	1,778,155		1,884,843
Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	739,203		784,475
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	1,776		7,508
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	13,746,923		13,540,655
Total assets	15,219,210	[4]	15,008,982	[5]
Total liabilities	48,893		31,111
Fair Value, Measurements, Recurring | Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	4,340		4,609
Fair Value, Measurements, Recurring | Derivatives not designated as hedging instruments | Currency exchange risks | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	54,495		34,231
Fair Value, Measurements, Recurring | Derivatives not designated as hedging instruments | Currency exchange risks | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	45,727		28,363
Fair Value, Measurements, Recurring | Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant asset | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	124,456		116,604
Fair Value, Measurements, Recurring | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	2,907		2,546
Fair Value, Measurements, Recurring | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	3,166		2,748
Fair Value, Measurements, Recurring | Fair value accounting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	1,286,089		1,310,337
Fair Value, Measurements, Recurring | Fair value accounting | Venture capital and private equity fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	1,195,303		1,130,882
Fair Value, Measurements, Recurring | Fair value accounting | Other venture capital investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	78,850		71,204
Fair Value, Measurements, Recurring | Fair value accounting | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	11,936		108,251
Fair Value, Measurements, Recurring | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	7,914,125		7,302,273
Fair Value, Measurements, Recurring | U.S. agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	3,313,664		3,561,556
Fair Value, Measurements, Recurring | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	1,778,155		1,884,843
Fair Value, Measurements, Recurring | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	739,203		784,475
Fair Value, Measurements, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	1,776		7,508
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	7,915,507		7,306,563
Total assets	7,927,443	[4]	7,414,814	[5]
Total liabilities	0		0
Fair Value, Measurements, Recurring | Level 1 | Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	0		0
Fair Value, Measurements, Recurring | Level 1 | Derivatives not designated as hedging instruments | Currency exchange risks | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	0		0
Fair Value, Measurements, Recurring | Level 1 | Derivatives not designated as hedging instruments | Currency exchange risks | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	0		0
Fair Value, Measurements, Recurring | Level 1 | Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant asset | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	0		0
Fair Value, Measurements, Recurring | Level 1 | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	0		0
Fair Value, Measurements, Recurring | Level 1 | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	0		0
Fair Value, Measurements, Recurring | Level 1 | Fair value accounting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	11,936		108,251
Fair Value, Measurements, Recurring | Level 1 | Fair value accounting | Venture capital and private equity fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	0		0
Fair Value, Measurements, Recurring | Level 1 | Fair value accounting | Other venture capital investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	0		0
Fair Value, Measurements, Recurring | Level 1 | Fair value accounting | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	11,936		108,251
Fair Value, Measurements, Recurring | Level 1 | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	7,914,125		7,302,273
Fair Value, Measurements, Recurring | Level 1 | U.S. agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 1 | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 1 | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 1 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	1,382		4,290
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	5,831,416		6,234,092
Total assets	5,895,353	[4]	6,277,384	[5]
Total liabilities	48,893		31,111
Fair Value, Measurements, Recurring | Level 2 | Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	4,340		4,609
Fair Value, Measurements, Recurring | Level 2 | Derivatives not designated as hedging instruments | Currency exchange risks | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	54,495		34,231
Fair Value, Measurements, Recurring | Level 2 | Derivatives not designated as hedging instruments | Currency exchange risks | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	45,727		28,363
Fair Value, Measurements, Recurring | Level 2 | Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant asset | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	2,195		1,906
Fair Value, Measurements, Recurring | Level 2 | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	2,907		2,546
Fair Value, Measurements, Recurring | Level 2 | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	3,166		2,748
Fair Value, Measurements, Recurring | Level 2 | Fair value accounting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	0		0
Fair Value, Measurements, Recurring | Level 2 | Fair value accounting | Venture capital and private equity fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	0		0
Fair Value, Measurements, Recurring | Level 2 | Fair value accounting | Other venture capital investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	0		0
Fair Value, Measurements, Recurring | Level 2 | Fair value accounting | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	0		0
Fair Value, Measurements, Recurring | Level 2 | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 2 | U.S. agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	3,313,664		3,561,556
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	1,778,155		1,884,843
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	739,203		784,475
Fair Value, Measurements, Recurring | Level 2 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	394		3,218
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Total assets	1,396,414	[4]	1,316,784	[5]
Total liabilities	0		0
Fair Value, Measurements, Recurring | Level 3 | Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	0		0
Fair Value, Measurements, Recurring | Level 3 | Derivatives not designated as hedging instruments | Currency exchange risks | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	0		0
Fair Value, Measurements, Recurring | Level 3 | Derivatives not designated as hedging instruments | Currency exchange risks | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	0		0
Fair Value, Measurements, Recurring | Level 3 | Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant asset | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	122,261		114,698
Fair Value, Measurements, Recurring | Level 3 | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	0		0
Fair Value, Measurements, Recurring | Level 3 | Derivatives not designated as hedging instruments | Other derivative instruments | Client interest rate derivatives | Other liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Liabilities	0		0
Fair Value, Measurements, Recurring | Level 3 | Fair value accounting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	1,274,153		1,202,086
Fair Value, Measurements, Recurring | Level 3 | Fair value accounting | Venture capital and private equity fund investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	1,195,303		1,130,882
Fair Value, Measurements, Recurring | Level 3 | Fair value accounting | Other venture capital investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	78,850		71,204
Fair Value, Measurements, Recurring | Level 3 | Fair value accounting | Other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-marketable securities	0		0
Fair Value, Measurements, Recurring | Level 3 | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 3 | U.S. agency debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Fixed rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage-backed securities | Agency-issued collateralized mortgage obligations | Variable rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Fair Value, Measurements, Recurring | Level 3 | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	0		0
Noncontrolling Interests | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	9,100		100,000
Noncontrolling Interests | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 1,200,000		$ 1,100,000

[1] 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.

[2] 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.

[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] Included in Level 1 and Level 3 assets are $9 million and $1.2 billion, respectively, attributable to noncontrolling interests calculated based on the ownership percentages of the noncontrolling interests.

[5] Included in Level 1 and Level 3 assets are $100 million and $1.1 billion, respectively, attributable to noncontrolling interests calculated based on the ownership percentages of the noncontrolling interests.