Loans and Allowance for Loan Losses - Recorded Investment in Loans Modified in TDRs (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	$ 1,375	[1]	$ 3,706	[1]
Commercial loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	1,275		3,421
Commercial loans | Software
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	0		600
Commercial loans | Venture capital/private equity
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	821		0
Commercial loans | Life science
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	454		0
Commercial loans | Premium wine
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	0		405
Commercial loans | Other
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	0		2,416
Consumer loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	100		285
Consumer loans | Real estate secured loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	0		249
Consumer loans | Consumer loans
Financing Receivable, Modifications [Line Items]
Loans modified in TDRs during the period	$ 100		$ 36

[1] During the three months ended March 31, 2013, we had no partial charge-offs of loans classified as TDRs. There were partial charge-offs of $0.8 million on loans classified as TDRs during the three months ended March 31, 2012.