Loans - Pre-Modification and Post-Modification Outstanding Recorded Investments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Contract		Dec. 31, 2011 Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	100		42
Pre-Modification Outstanding Recorded Investment	$ 99,494		$ 46,749
Post-Modification Outstanding Recorded Investment	90,348		46,346
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	20	[1]	27	[1]
Pre-Modification Outstanding Recorded Investment	40,785	[1]	29,142	[1]
Post-Modification Outstanding Recorded Investment	36,066	[1]	28,866	[1]
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	18		7
Pre-Modification Outstanding Recorded Investment	40,499		12,890
Post-Modification Outstanding Recorded Investment	39,535		12,777
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	5		2
Pre-Modification Outstanding Recorded Investment	7,092		3,422
Post-Modification Outstanding Recorded Investment	4,885		3,422
Commercial real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	23		9
Pre-Modification Outstanding Recorded Investment	47,591		16,312
Post-Modification Outstanding Recorded Investment	44,420		16,199
Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	43		5
Pre-Modification Outstanding Recorded Investment	10,133		1,237
Post-Modification Outstanding Recorded Investment	9,125		1,223
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	14		1
Pre-Modification Outstanding Recorded Investment	985		58
Post-Modification Outstanding Recorded Investment	$ 737		$ 58

[1] Includes 9 finance leases with pre and post modification outstanding recorded investments totalling $372 thousand and 294 thousand, respectively, for the year ended December 31, 2011. During 2012, the finance leases were immaterial.