Loans - Average Recorded Investment and Interest Income Recognized on Impaired Loans by Loan Class (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 46,271	$ 40,493	$ 38,492
Interest Income Recognized	479	482	581
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	7,239	1,211	1,184
Interest Income Recognized	82	7	1
Commercial real estate: Construction [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	82	1,087
Interest Income Recognized	0	0	3
Commercial real estate: Other [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	24,186	22,486	17,181
Interest Income Recognized	291	385	347
Residential: 1-4 family [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	13,971	16,036	17,778
Interest Income Recognized	80	75	163
Residential: Home equities [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	875	678	1,262
Interest Income Recognized	$ 26	$ 15	$ 67