Investment Securities - Non-marketable and Other Securities (Detail) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) Investment	Jun. 30, 2016 USD ($) Investment	Jun. 30, 2017 USD ($) Investment	Jun. 30, 2016 USD ($) Investment	Dec. 31, 2016 USD ($) Investment
Investment Holdings [Line Items]
Total non-marketable and other securities	$ 630,670		$ 630,670		$ 622,552
Upper Limit
Investment Holdings [Line Items]
Equity method investment voting ownership percentage	5.00%		5.00%
Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	$ 788		$ 788		753
Venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	135,438		135,438		141,649
Non-marketable securities, cost method accounting	223,500	$ 221,700	223,500	$ 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	16,841		$ 16,841		$ 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	57,640		$ 57,640		$ 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	60,957		$ 60,957		$ 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		$ 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	85,609		$ 85,609		$ 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	6,797		$ 6,797		$ 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	19,443		$ 19,443		$ 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	25,398		$ 25,398		$ 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	13,557		$ 13,557		$ 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	7,623		$ 7,623		$ 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	12,791		$ 12,791		$ 10,297
Venture capital and private equity fund investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	$ 110,001		$ 110,001		$ 114,606
Number of investments | Investment	244	264	244	264	252
Other venture capital investments | Fair value accounting
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	$ 1,897		$ 1,897		$ 2,040
Other venture capital investments | Fair value accounting | Silicon Valley BancVentures, LP
Investment Holdings [Line Items]
Non-marketable securities, fair value accounting	1,897		$ 1,897		$ 2,040
Percentage of ownership			10.70%		10.70%
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	16,476		$ 16,476		$ 17,020
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP
Investment Holdings [Line Items]
Non-marketable securities, equity method accounting	13,159		$ 13,159		$ 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	3,317		$ 3,317		$ 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	113,322		$ 113,322		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	75,052		$ 75,052		$ 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	38,270		$ 38,270		$ 48,218
Other investments | Cost method accounting
Investment Holdings [Line Items]
Non-marketable securities, cost method accounting	26,758		26,758		$ 27,700
Low income housing tax credit funds
Investment Holdings [Line Items]
Affordable Housing Tax Credits and Other Tax Benefits, Amount	3,968	$ 4,066	8,660	$ 8,132
Amortization Method Qualified Affordable Housing Project Investments, Amortization	$ 3,385	$ 3,578	$ 6,621	$ 7,190