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	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	$ 23,232	$ 22,433
Commercial loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	22,782	21,763
Consumer loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	450	670
Software
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	10,509	5,860
Hardware
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	7,541	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	2,058	1,442
Other
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	2,674	1,055
Consumer loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs	$ 450	$ 670