Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended		1 Months Ended		6 Months Ended					1 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Restricted Stock	Dec. 31, 2012 Restricted Stock	Aug. 31, 2012 2012 Equity Incentive Plan	Jun. 30, 2013 2012 Equity Incentive Plan	Jun. 30, 2013 2012 Equity Incentive Plan Restricted Stock	Jun. 30, 2012 2012 Equity Incentive Plan Restricted Stock	Jun. 30, 2013 2012 Equity Incentive Plan Restricted Stock Minimum	Jun. 30, 2013 2012 Equity Incentive Plan Restricted Stock Maximum	Jun. 30, 2013 2012 Equity Incentive Plan Restricted Stock and Performance Shares	Aug. 31, 2012 Previously Approved Plans	Jun. 30, 2013 Previously Approved Plans Restricted Stock	Jun. 30, 2013 2012 Plan and Previously Approved Plans	Jun. 30, 2013 2012 Plan and Previously Approved Plans Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares initially authorized for issuance under equity incentive plan								300,000
Additional shares authorized for issuance under equity incentive plan								17,666
Shares ceased to be issuable															17,666
Outstanding options to purchase shares of common stock	328,000		328,000		433,000												328,000
Unvested restricted shares outstanding						374,497	312,501											374,497
Outstanding shares remained available for future grants									276,030
Restricted shares outstanding																0
Vesting period												3 years	4 years
Performance based restricted stock granted														167,500
Unrecognized compensation cost related to the nonvested options										$ 908,319	$ 821,210
Unrecognized compensation costs are expected to be recognized over a weighted average period (years)										2 years 1 month 6 days	2 years 1 month 6 days
Restricted shares outstanding expected to vest																206,997
Aggregate intrinsic value						724,490
Share-base compensation expense	$ 59,000	$ 120,000	$ 164,000	$ 219,000