Summary of Stock Option Transactions (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012
Number of Options
Beginning Balance	497,539
Options Exchanged	182,335
Cancelled	(157,500)
Forfeited	(19,901)
Ending Balance	502,473
Vested or expected to vest	502,384
Exercisable at end of period	280,084
Avg. Strike
Beginning Balance	$ 11.47
Options Exchanged	$ 11.54
Cancelled	$ 10.45
Forfeited	$ 12.09
Ending Balance	$ 11.79
Vested or expected to vest	$ 11.79
Exercisable at end of period	$ 11.57
Weighted Average Remaining Contractual Term
Beginning Balance	4 years 6 months
Ending Balance	4 years 6 months
Vested or expected to vest	4 years 6 months
Exercisable at end of period	8 years 10 months 24 days
Aggregate Intrinsic Value
Beginning Balance	$ 101,360
Ending Balance	41,969
Vested or expected to vest	41,969
Exercisable at end of period	$ 41,969