Loans - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Receivables [Abstract]
Percentage of outstanding principal balances of commercial real estate loans secured by owner-occupied properties	75.00%		77.00%
Loans serviced for others	$ 69,400,000		$ 70,200,000
Concentrations of loans related to a single industry	0		0
Troubled debt restructurings, loans	8,700,000		8,600,000
Reserves allocated to customers whose loan terms are modified in troubled debt restructurings	525,000		583,000
Loans classified as troubled debt restructurings	8,000,000
Loans payable in nonaccrual of interest status	711,000
Loans restructured, subsequently defaulted	0	0
Outstanding balance of commercial loans classified under credit risk, minimum amount	275,000
Loans listed as not rated under risk category, maximum amount	$ 275,000
Non-performing loans past due days and greater	90 days