Off-Balance Sheet Arrangements, Guarantees and Other Commitments - Total Capital Commitments, Unfunded Capital Commitments, and Our Ownership in Each Fund (Additional Information) (Detail) (Venture capital and private equity fund investments)	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
SVB Capital Partners II, LP | Fair value accounting
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	5.10%	[1]	5.10%	[1]
SVB Capital Partners II, LP | Fair value accounting | Direct ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	1.30%
SVB Capital Partners II, LP | Fair value accounting | Indirect ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	3.80%
Other private equity fund | Fair value accounting
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	58.20%	[2]	58.20%	[2]
Other private equity fund | Fair value accounting | Direct ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	41.50%
Other fund investments
Venture Capital and Private Equity Fund Investments [Line Items]
Number of other funds with investment commitments	283
Upper Limit | Other fund investments
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	5.00%
SVB Capital—NT Growth Partners, LP | Other private equity fund | Fair value accounting | Indirect ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	12.60%
SVB Capital Preferred Return Fund, LP | Other private equity fund | Fair value accounting | Indirect ownership interest
Venture Capital and Private Equity Fund Investments [Line Items]
Percentage of ownership	4.10%

[1] At March 31, 2015, we had a direct ownership interest of 1.3 percent and an indirect ownership interest of 3.8 percent in the fund through our ownership interest of SVB Strategic Investors Fund II, LP.

[2] At March 31, 2015, we had a direct ownership interest of 41.5 percent and indirect ownership interests of 12.6 percent and 4.1 percent in the fund through our ownership interest of SVB Capital—NT Growth Partners, LP and SVB Capital Preferred Return Fund, LP, respectively.