Investment Securities - Non-marketable and Other Securities (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) Investment	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Investment Holdings [Line Items]
Total non-marketable and other securities	$ 668,497		$ 674,946
Upper Limit
Investment Holdings [Line Items]
Equity Method Investment Voting Ownership Percentage		27700.00%	5.00%
Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	468		$ 548
Venture capital and private equity fund investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	83,555		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	9,326		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	22,225		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	25,570		26,411
Venture capital and private equity fund investments | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	26,434		25,333
Venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	145,649		152,237
Non-marketable securities, cost method accounting	233,000		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	$ 20,538		$ 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	$ 58,156		$ 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	$ 59,744		$ 62,983
Percentage of ownership	33.00%		33.00%
Venture capital and private equity fund investments | Fair value accounting | SVB Capital Partners II, LP | Direct ownership interest
Investment Holdings [Line Items]
Percentage of ownership	1.30%
Venture capital and private equity fund investments | Fair value accounting | SVB Capital Partners II, LP | Indirect ownership interest
Investment Holdings [Line Items]
Percentage of ownership	3.80%
Venture capital and private equity fund investments | Fair value accounting | Other private equity fund
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	$ 7,211		$ 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	$ 83,555		$ 85,705
Venture capital and private equity fund investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	$ 117,409		120,676
Number of investments | Investment	267
Other venture capital investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	$ 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
Percentage of ownership	10.70%		10.70%
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 21,809		$ 21,970
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 18,106		$ 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	$ 3,703		$ 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	$ 120,026		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	$ 79,260		$ 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	$ 40,766		$ 39,733
Other investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	19,797		18,882
Low Income Housing Tax Credit Funds
Investment Holdings [Line Items]
Nonmarketable securities, other	157,744		154,356
Tax credits and other tax benefits recognized	4,207	$ 3,213
Amortization expense included in provision for income taxes	$ 3,612	$ 2,797
Unfunded commitments
Investment Holdings [Line Items]
Accrued expenses and other liabilities			$ 90,978