Share Based Compensation - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued upon exercise of stock options and awards	0	300,000	300,000	500,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted options	527,445	462,000	571,445	502,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted restricted stock awards	601,445	643,750	723,062	688,750