Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended				1 Months Ended			1 Months Ended				1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Unvested Restricted Common Stock	Jul. 16, 2012 Vested options held by 3 employees	Jul. 16, 2012 Vested options held by 3 employees Minimum	Jul. 16, 2012 Vested options held by 3 employees Maximum	Jul. 16, 2012 Unvested options held by 2 employees	Jul. 16, 2012 Unvested options held by 2 employees Minimum	Jul. 16, 2012 Unvested options held by 2 employees Maximum	Jun. 14, 2013 Vested options held by 1 employees	May 31, 2013 Vested options held by 1 employees	Jun. 14, 2013 Vested options held by 1 employees Minimum	May 31, 2013 Vested options held by 1 employees Minimum	Jun. 14, 2013 Vested options held by 1 employees Maximum	May 31, 2013 Vested options held by 1 employees Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, granted	125,000	76,300	1,551,400	508,700
Weighted-average grant date fair value	$ 2.47	$ 3.95	$ 1.94	$ 3.56
Unrecognized compensation costs	$ 8.8		$ 8.8
Expected recognition period			1 year 8 months 5 days		1 year 3 months 26 days
Share Based Compensation Arrangement By Share Based Payment Award Option Fully Vested						829,488						71,167	66,667
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period							12 months	18 months		6 months	12 months			3 months	3 months	12 months	12 months
Share Based Compensation Arrangement By Share Based Payment Award Unvested Options									200,000
Share Based Compensation Arrangement By Share Based Payment Award Unvested Shares Of Restricted Stocks									147,427
Unrecognized compensation costs					$ 1.5