Stockholder's Equity - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
	Oct. 31, 2010	Sep. 30, 2013	Sep. 30, 2012
Stockholders Equity Textual [Abstract]
Common stock reserved and available for issuance		1,500,000
Percentage of directors' stock grant vested on one year anniversary date		100.00%
Period of Vested Shares		5 years
Granted, Weighted average grant date fair value		$ 21.21
Share based award, settled in cash		$ 2,700
Share based payment description		The amount of cash payment will equal the fair market value of 2,700 shares on the settlement date
Total unrecognized compensation cost related to nonvested shares of common stock granted		8,500,000
Weighted average period of cost recognized		3 years 3 months 11 days
Total fair value of shares of common stock vested		3,800,000	3,500,000
Compensation expense related to nonvested stock grants		2,900,000	3,400,000
Price of shares issued under Employee Stock Purchase Plan as a percentage of FMV		95.00%
Number of shares reserved for the Employee Stock Purchase Plan		250,000
Additional shares authorized for issuance		250,000
Stock options issued and exercisable		15,000
Options exercised		0
Options forfeited		0
Options granted		0
Shares redeemed to satisfy personal tax obligations		37,353
Values of shares redeemed to satisfy personal tax obligations		794,000
Total amount authorized for repurchase under Company's Stock Repurchase Program	50,000,000
Number of shares of common stock repurchased during period		0
Number of shares of common stock reissued from treasury shares		0
Remaining amount authorized for repurchase under Company's Stock Repurchase Program		$ 22,500,000
Director [Member]
Stockholders Equity Textual [Abstract]
Non vested stock grants to Independent director		24,300
Director Period of Vested Shares		1 year
Employee [Member]
Stockholders Equity Textual [Abstract]
Nonvested stock grants to employees		181,648
Employee Purchase Plan [Member]
Stockholders Equity Textual [Abstract]
Additional shares authorized for issuance		250,000