Stock Plans and Other Incentives - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended			9 Months Ended				1 Months Ended		9 Months Ended			12 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2014 Employees	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Minimum [Member]	Sep. 30, 2014 Maximum [Member]	Sep. 30, 2014 RSU [Member]	Sep. 30, 2013 RSU [Member]	Feb. 28, 2014 RSU [Member] Employees [Member]	Feb. 28, 2013 RSU [Member] Employees [Member]	Sep. 30, 2014 RSU [Member] Non-Employee Directors [Member]	Sep. 30, 2013 RSU [Member] Non-Employee Directors [Member]	Sep. 30, 2014 Money Option [Member]	Dec. 31, 2013 Money Option [Member]	Sep. 30, 2014 Non-Employee Directors Compensation Plan [Member]	Sep. 30, 2013 Non-Employee Directors Compensation Plan [Member]	Sep. 30, 2014 Non-Employee Directors Compensation Plan [Member]	Sep. 30, 2013 Non-Employee Directors Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of the awards granted under the company's incentive plans				10 years
Vesting period for incentive plans	5 years						3 years	5 years
Options granted, shares	20,000			20,000
Options granted, number of employees	1
Options granted, vesting percentage	20.00%
Options, granted price per share	$ 18.52			$ 18.52
Fair value granted per option	$ 7.64
Liability for option cancellations amount		$ 172,809		$ 172,809		$ 268,341									$ 173,000	$ 268,000
Closing stock price		$ 23.59	$ 16.15	$ 23.59	$ 16.15	$ 19.23
Outstanding in-the-money options				8,862	35,448										8,862	17,724
Recorded compensation expense (benefit)		22,000	(83,000)	36,000	111,000
RSUs granted									96,771	100,328	91,431	91,356	5,340	8,972
Weighted average grant date fair value											$ 18.13	$ 16.20	$ 19.37	$ 15.37
Vesting rights									RSUs vest one-third a year over three years
Number of months after the termination of service, RSUs delivered to non-employee directors									6 months
Non-cash compensation expense		$ 415,000	$ 412,000	$ 1,271,489	$ 1,451,337												$ 34,500	$ 46,000	$ 103,500	$ 138,000