Investment Securities - Non-marketable and Other Securities (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) Investment	Mar. 31, 2016 USD ($) Investment	Dec. 31, 2016 USD ($) Investment
Investment Holdings [Line Items]
Total non-marketable and other securities	$ 635,550		$ 622,552
Upper Limit
Investment Holdings [Line Items]
Equity method investment voting ownership percentage	5.00%
Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	$ 646		753
Venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	139,715		141,649
Non-marketable securities, cost method accounting	223,700	$ 221,700
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	$ 18,048		$ 18,459
Percentage of ownership	12.60%		12.60%
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 | SVB Capital Preferred Return Fund, LP
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	$ 59,225		$ 57,627
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	$ 62,442		$ 59,718
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	$ 0		$ 5,845
Percentage of ownership	0.00%		58.20%
Venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 85,529		$ 82,823
Venture capital and private equity fund investments | Equity method accounting | SVB Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 7,540		$ 7,720
Percentage of ownership	8.60%		8.60%
Venture capital and private equity fund investments | Equity method accounting | SVB Strategic Investors Fund III, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 20,188		$ 20,449
Percentage of ownership	5.90%		5.90%
Venture capital and private equity fund investments | Equity method accounting | SVB Strategic Investors Fund IV, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 26,342		$ 24,530
Percentage of ownership	5.00%		5.00%
Venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund V Funds
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 12,521		$ 12,029
Venture capital and private equity fund investments | Equity method accounting | SVB Capital Partners II, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 7,568		$ 7,798
Percentage of ownership	5.10%		5.10%
Venture capital and private equity fund investments | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 11,370		$ 10,297
Venture capital and private equity fund investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	$ 117,243		$ 114,606
Number of investments | Investment	249	267	252
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	$ 16,509		$ 17,020
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 12,888		$ 13,557
Percentage of ownership	15.50%		15.50%
Debt funds | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 3,621		$ 3,463
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	$ 112,665		123,514
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	$ 75,316		$ 75,296
Percentage of ownership	50.00%		50.00%
Other investments | Equity method accounting | Other investments
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	$ 37,349		$ 48,218
Other investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	28,437		$ 27,700
Low income housing tax credit funds
Investment Holdings [Line Items]
Tax credits and other tax benefits recognized	4,692	$ 4,207
Amortization expense included in provision for income taxes	$ 3,236	$ 3,612