Summary of Activity for Company's Non-vested Options (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013
Number of Shares
Non-vested options - beginning	54,416
Granted	20,229
Vested	(29,110)
Forfeited or expired	0
Non-vested options - ending	45,535
Weighted Average Grant-Date Fair Value
Non-vested options - beginning	$ 7.56
Granted	$ 7.99
Vested	$ 7.34
Forfeited or expired	$ 0.00
Non-vested options - ending	$ 7.89