Investment Securities - Non-marketable and Other Securities (Detail) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($) Investment	Sep. 30, 2015 USD ($) Investment	Sep. 30, 2016 USD ($) Investment	Sep. 30, 2015 USD ($) Investment	Dec. 31, 2015 USD ($) Investment
Investment Holdings [Line Items]
Total non-marketable and other securities	$ 625,178		$ 625,178		$ 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	579		579		$ 548
Venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	141,841		141,841		152,237
Non-marketable securities, equity method accounting	84,904		84,904		85,705
Non-marketable securities, cost method accounting	218,000		218,000		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	17,940		$ 17,940		$ 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]
Non-marketable securities, equity method accounting	9,133		$ 9,133		$ 10,035
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]
Non-marketable securities, equity method accounting	21,369		$ 21,369		$ 23,926
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]
Non-marketable securities, equity method accounting	25,737		$ 25,737		$ 26,411
Percentage of ownership			5.00%		5.00%
Venture capital and private equity fund investments | Fair value accounting | Strategic Investors Fund V Funds
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	11,715		$ 11,715		$ 10,470
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	57,488		$ 57,488		$ 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	59,692		$ 59,692		$ 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	6,721		$ 6,721		$ 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 | Fair value accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	16,950		$ 16,950		$ 14,863
Venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	84,904		84,904		85,705
Venture capital and private equity fund investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	$ 115,113		$ 115,113		$ 120,676
Number of investments | Investment	255	270	255	270	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	18,971		$ 18,971		$ 21,970
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	15,496		$ 15,496		$ 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	3,475		$ 3,475		$ 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	128,422		$ 128,422		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	77,817		$ 77,817		$ 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	50,605		$ 50,605		$ 39,733
Other investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	26,834		26,834		18,882
Low income housing tax credit funds
Investment Holdings [Line Items]
Nonmarketable securities, other	106,474		106,474		154,356
Tax credits and other tax benefits recognized	3,995	$ 4,780	12,127	$ 11,207
Amortization expense included in provision for income taxes	2,556	$ 2,011	9,746	$ 7,549
Unfunded commitments
Investment Holdings [Line Items]
Accrued expenses and other liabilities	$ 52,846		$ 52,846		$ 90,978