Stock Option Plan and Stock Grants - Additional Information (Detail) (USD $)	1 Months Ended				3 Months Ended		9 Months Ended		1 Months Ended
	May 31, 2013	Apr. 30, 2013	Mar. 31, 2013	Jan. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	May 31, 2013 Restricted Stock [Member] Director [Member]	Mar. 31, 2013 Restricted Stock [Member] Director [Member]	Jan. 31, 2013 Restricted Stock [Member] Director [Member]	May 31, 2013 Restricted Stock [Member] Director [Member] Phase one	Mar. 31, 2013 Restricted Stock [Member] Director [Member] Phase one	Jan. 31, 2013 Restricted Stock [Member] Director [Member] Phase one	May 31, 2013 Restricted Stock [Member] Director [Member] Phase two	Mar. 31, 2013 Restricted Stock [Member] Director [Member] Phase two	Jan. 31, 2013 Restricted Stock [Member] Director [Member] Phase two	May 31, 2013 Restricted Stock [Member] Director [Member] Phase three	Mar. 31, 2013 Restricted Stock [Member] Director [Member] Phase three	Jan. 31, 2013 Restricted Stock [Member] Director [Member] Phase three	Apr. 30, 2013 Restricted Stock [Member] Senior Management	Feb. 28, 2013 Restricted Stock [Member] Senior Management
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization of stock-related compensation					$ 1,600,000	$ 1,200,000	$ 4,332,000	$ 4,465,000
Stockholders' Equity Note, Stock Split, Conversion Ratio					2
Share based compensation, grants awarded									40,000	666	62,000										2,000	68,666
Share based compensation, fair market value									$ 1,700,000	$ 0	$ 2,200,000										$ 80,200	$ 2,500,000
Share based compensation, vesting description	One-third of the shares of restricted common stock covered by these awards vest on each of November 8, 2013, May 8, 2014, and May 8, 2015	These Restricted Stock Grants will vest on December 31, 2013.	One-third of the shares of restricted common stock covered by these awards vests on each of September 13, 2013, March 13, 2014, and March 13, 2015.	These Restricted Stock Grants will vest on December 31, 2013.One-third of the shares of restricted common stock covered by these awards vest on each of December 31, 2013, December 31, 2014, and December 31, 2015.
Share based compensation, restricted stock, vesting date												Nov. 08, 2013	Sep. 13, 2013	Dec. 31, 2013	May 08, 2014	Mar. 13, 2014	Dec. 31, 2014	May 08, 2015	Mar. 13, 2015	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2013