Loans - Pre-Modification and Post-Modification Outstanding Recorded Investments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 Contract	Mar. 31, 2014 Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	8	17
Pre-Modification Outstanding Recorded Investment	$ 6,864	$ 30,535
Post-Modification Outstanding Recorded Investment	6,812	28,980
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	6	11
Pre-Modification Outstanding Recorded Investment	1,584	9,762
Post-Modification Outstanding Recorded Investment	1,534	9,093
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	1	5
Pre-Modification Outstanding Recorded Investment	5,000	15,946
Post-Modification Outstanding Recorded Investment	5,000	15,060
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	0	1
Pre-Modification Outstanding Recorded Investment	0	4,827
Post-Modification Outstanding Recorded Investment	0	4,827
Commercial Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	1	6
Pre-Modification Outstanding Recorded Investment	5,000	20,773
Post-Modification Outstanding Recorded Investment	5,000	19,887
Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts	1	0
Pre-Modification Outstanding Recorded Investment	280	0
Post-Modification Outstanding Recorded Investment	$ 278	$ 0