Loans - Average Recorded Investment and Interest Income Recognized on Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	$ 158,807	$ 220,071	$ 175,256	$ 219,352
Interest Income Recognized	1,168	1,324	4,205	4,426
Commercial Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	99,999	131,683	109,725	132,744
Interest Income Recognized	751	635	2,618	2,391
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	3,039	1,158	1,855	1,182
Interest Income Recognized	18	29	47	55
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	30,387	59,874	37,229	57,069
Interest Income Recognized	172	415	831	1,203
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	83,045	109,226	91,184	112,216
Interest Income Recognized	604	612	2,173	2,229
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	16,954	22,457	18,541	20,528
Interest Income Recognized	147	23	445	162
Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	25,382	27,356	26,447	28,357
Interest Income Recognized	227	245	709	777
Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average Recorded Investment	3,039	1,158	1,855	1,182
Interest Income Recognized	$ 18	$ 29	$ 47	$ 55