Investment Securities - Non-marketable and Other Securities (Detail) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($) Investment	Jun. 30, 2015 USD ($) Investment	Jun. 30, 2016 USD ($) Investment	Jun. 30, 2015 USD ($) Investment	Dec. 31, 2015 USD ($) Investment	Dec. 31, 2014
Investment Holdings [Line Items]
Total non-marketable and other securities	$ 664,054		$ 664,054		$ 674,946
Upper Limit
Investment Holdings [Line Items]
Equity method investment voting ownership percentage		5.00%		5.00%		5.00%
Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	280		280		548
Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	82,214		82,214		85,705
Venture capital and private equity fund investments | SVB Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	8,996		8,996		10,035
Venture capital and private equity fund investments | SVB Strategic Investors Fund III, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	20,957		20,957		23,926
Venture capital and private equity fund investments | SVB Strategic Investors Fund IV, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	24,557		24,557		26,411
Venture capital and private equity fund investments | Strategic Investors Fund V Funds
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	11,463		11,463		10,470
Venture capital and private equity fund investments | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	16,241		16,241		14,863
Venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	144,227		144,227		152,237
Non-marketable securities, cost method accounting	227,000		227,000		233,000
Venture capital and private equity fund investments | Fair value accounting | SVB Strategic Investors Fund, LP
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	18,062		$ 18,062		$ 20,794
Percentage of ownership			12.60%		12.60%
Venture capital and private equity fund investments | Fair value accounting | SVB Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Percentage of ownership			8.60%		8.60%
Venture capital and private equity fund investments | Fair value accounting | SVB Strategic Investors Fund III, LP
Investment Holdings [Line Items]
Percentage of ownership			5.90%		5.90%
Venture capital and private equity fund investments | Fair value accounting | SVB Strategic Investors Fund IV, LP
Investment Holdings [Line Items]
Percentage of ownership			5.00%		5.00%
Venture capital and private equity fund investments | Fair value accounting | SVB Capital Preferred Return Fund, LP
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	58,220		$ 58,220		$ 60,619
Percentage of ownership			20.00%		20.00%
Venture capital and private equity fund investments | Fair value accounting | SVB Capital—NT Growth Partners, LP
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	60,789		$ 60,789		$ 62,983
Percentage of ownership			33.00%		33.00%
Venture capital and private equity fund investments | Fair value accounting | Other private equity fund
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	7,156		$ 7,156		$ 7,841
Percentage of ownership			58.20%		58.20%
Venture capital and private equity fund investments | Fair value accounting | Other private equity fund | Direct ownership interest
Investment Holdings [Line Items]
Percentage of ownership			41.50%
Venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	82,214		$ 82,214		$ 85,705
Venture capital and private equity fund investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	$ 117,379		$ 117,379		$ 120,676
Number of investments | Investment	264	273	264	273	267
Other venture capital investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	$ 2,040		$ 2,040		$ 2,040
Other venture capital investments | Fair value accounting | Silicon Valley BancVentures, LP
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	2,040		$ 2,040		$ 2,040
Percentage of ownership			10.70%		10.70%
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	19,239		$ 19,239		$ 21,970
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	15,705		$ 15,705		$ 17,453
Percentage of ownership			15.50%		15.50%
Debt funds | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	3,534		$ 3,534		$ 4,517
Other investments | Fair value accounting | SVB Capital Preferred Return Fund, LP | Indirect ownership interest
Investment Holdings [Line Items]
Percentage of ownership			4.10%
Other investments | Fair value accounting | SVB Capital—NT Growth Partners, LP | Indirect ownership interest
Investment Holdings [Line Items]
Percentage of ownership			12.60%
Other investments | Fair value accounting | Other private equity fund | Direct ownership interest
Investment Holdings [Line Items]
Percentage of ownership			41.50%
Other investments | Equity method accounting
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	120,721		$ 120,721		118,532
Other investments | Equity method accounting | Gold Hill Capital 2008, LP | Direct ownership interest
Investment Holdings [Line Items]
Percentage of ownership			11.50%
Other investments | Equity method accounting | Gold Hill Capital 2008, LP | Indirect ownership interest
Investment Holdings [Line Items]
Percentage of ownership			4.00%
Other investments | Equity method accounting | China Joint Venture investment
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	78,074		$ 78,074		$ 78,799
Percentage of ownership			50.00%		50.00%
Other investments | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	42,647		$ 42,647		$ 39,733
Other investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	24,156		24,156		18,882
Low income housing tax credit funds
Investment Holdings [Line Items]
Nonmarketable securities, other	153,798		153,798		154,356
Tax credits and other tax benefits recognized	4,066	$ 3,214	8,132	$ 6,427
Amortization expense included in provision for income taxes	3,578	$ 2,741	7,190	$ 5,538
Unfunded commitments
Investment Holdings [Line Items]
Accrued expenses and other liabilities	$ 72,231		$ 72,231		$ 90,978