Loans and Allowance for Loan Losses - Summary of Loans Modified in Troubled Debt Restructurings ("TDRs") by Portfolio Segment and Class of Financing Receivables (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014 troubled_debt_restructuring	Dec. 31, 2013
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	10
Loans modified in TDRs	$ 10,300	$ 22,433
Software
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	7,848	5,860
Hardware
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	0	13,329
Venture capital/private equity
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	0	77
Premium wine
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	1,953	1,442
Other
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	275	1,055
Commercial loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	10,076	21,763
Consumer loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	224	670
Consumer loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	$ 224	$ 670