Loans and Allowance for Loan Losses Impaired Loans and Allowance for Loan Losses, Broken out by Portfolio Segment and Class of Financing Receivable (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable Unpaid Principal Balance Previously Reported		$ 55,400,000
Carrying value of impaired loans	51,649,000	38,279,000
Total unpaid principal of impaired loans	73,271,000	66,242,000
Software
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	27,618,000	3,263,000
Total unpaid principal of impaired loans	28,316,000	4,475,000
Hardware
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	19,667,000	21,863,000
Total unpaid principal of impaired loans	35,317,000	38,551,000	[1]
Venture capital/private equity
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	40,000
Total unpaid principal of impaired loans	40,000
Life science
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	1,278,000	0
Total unpaid principal of impaired loans	4,727,000	0
Premium wine
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	1,442,000	4,398,000
Total unpaid principal of impaired loans	1,778,000	4,716,000
Commercial, Other
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	690,000	5,415,000
Total unpaid principal of impaired loans	718,000	9,859,000
Commercial loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	50,735,000	34,939,000
Total unpaid principal of impaired loans	70,896,000	57,601,000
Real estate secured loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	244,000	2,239,000
Total unpaid principal of impaired loans	1,434,000	7,341,000	[1]
Consumer, Other
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	670,000	1,101,000
Total unpaid principal of impaired loans	941,000	1,300,000
Consumer loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	914,000	3,340,000
Total unpaid principal of impaired loans	2,375,000	8,641,000
Impaired loans for which there is no related allowance for loan losses
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	3,612,000	12,124,000
Impaired loans for which there is no related allowance for loan losses | Software
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	310,000	72,000
Impaired loans for which there is no related allowance for loan losses | Hardware
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	338,000	0
Impaired loans for which there is no related allowance for loan losses | Venture capital/private equity
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	0
Impaired loans for which there is no related allowance for loan losses | Life science
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	1,278,000	0
Impaired loans for which there is no related allowance for loan losses | Premium wine
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	1,442,000	4,398,000
Impaired loans for which there is no related allowance for loan losses | Commercial, Other
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	0	5,415,000
Impaired loans for which there is no related allowance for loan losses | Commercial loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	3,368,000	9,885,000
Impaired loans for which there is no related allowance for loan losses | Real estate secured loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	244,000	2,239,000
Impaired loans for which there is no related allowance for loan losses | Consumer, Other
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	0	0
Impaired loans for which there is no related allowance for loan losses | Consumer loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	244,000	2,239,000
Impaired loans for which there is a related allowance for loan losses
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	48,037,000	26,155,000
Impaired loans for which there is a related allowance for loan losses | Software
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	27,308,000	3,191,000
Impaired loans for which there is a related allowance for loan losses | Hardware
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	19,329,000	21,863,000
Impaired loans for which there is a related allowance for loan losses | Venture capital/private equity
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	40,000
Impaired loans for which there is a related allowance for loan losses | Life science
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	0	0
Impaired loans for which there is a related allowance for loan losses | Premium wine
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	0	0
Impaired loans for which there is a related allowance for loan losses | Commercial, Other
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	690,000	0
Impaired loans for which there is a related allowance for loan losses | Commercial loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	47,367,000	25,054,000
Impaired loans for which there is a related allowance for loan losses | Real estate secured loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	0	0
Impaired loans for which there is a related allowance for loan losses | Consumer, Other
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	670,000	1,101,000
Impaired loans for which there is a related allowance for loan losses | Consumer loans
Financing Receivable, Impaired [Line Items]
Carrying value of impaired loans	$ 670,000	$ 1,101,000

[1] The unpaid principal balances for hardware and real estate secured consumer loans as of December 31, 2012 have been corrected from previously reported amounts resulting in the total unpaid principal of impaired loans at December 31, 2012 changing from $55.4 million to $66.2 million.