Loans and Allowance for Loan Losses - Recorded Investment in Loans Modified in TDRs within Previous 12 months Subsequently Defaulted (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	$ 3,122	$ 885
Commercial loans
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	2,875	600
Commercial loans | Software
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	0	600
Commercial loans | Hardware
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	125	0
Commercial loans | Other
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	2,750	0
Consumer loans
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	247	285
Consumer loans | Real estate secured loans
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	247	249
Consumer loans | Consumer loans
Financing Receivable, Modifications [Line Items]
TDRs modified within the previous 12 months that defaulted in the period	$ 0	$ 36