Stock Option Plan and Stock Grants - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	May 31, 2014 Management [Member]	May 31, 2014 Director [Member]	May 13, 2014 Director [Member]	May 31, 2014 Restricted Stock [Member] Management [Member]	May 31, 2014 Restricted Stock [Member] Director [Member]	May 13, 2014 Restricted Stock [Member] Director [Member]	May 31, 2014 Restricted Stock [Member] Director [Member] Phase One [Member]	May 13, 2014 Restricted Stock [Member] Director [Member] Phase One [Member]	May 31, 2014 Restricted Stock [Member] Director [Member] Phase Two [Member]	May 13, 2014 Restricted Stock [Member] Director [Member] Phase Two [Member]	May 31, 2014 Restricted Stock [Member] Director [Member] Phase Three [Member]	May 13, 2014 Restricted Stock [Member] Director [Member] Phase Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization of stock-related compensation	$ 2,600,000	$ 1,600,000	$ 4,998,000	$ 4,332,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period								84,666	62,000	40,000
Deferred Compensation Arrangement with Individual, Shares Authorized for Issuance	3,750,000		3,750,000
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued								$ 3,600,000	$ 2,600,000	$ 1,700,000
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Date								Dec. 31, 2014			Dec. 31, 2014	Nov. 13, 2014	Dec. 31, 2015	May 13, 2015	Dec. 31, 2016	May 13, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights					These Restricted Stock Grants will vest on December 31, 2014.	One-third of the shares of restricted common stock covered by these awards vests on each of December 31, 2014, December 31, 2015, and December 31, 2016.	One-third of the shares of restricted common stock covered by these awards vests on each of November 13, 2014, May 13, 2015, and May 13, 2016.