Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended							1 Months Ended	3 Months Ended				1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Non-qualified stock options granted prior to May 2008	Dec. 31, 2012 Non-qualified stock options granted subsequent to April 2008	Dec. 31, 2012 Fiscal 2011 beginning on October 1, 2010 and ending on September 30, 2013	Dec. 31, 2012 Fiscal 2012 beginning on October 1, 2011 and ending on September 30, 2014	Dec. 31, 2012 Fiscal 2013 beginning on October 1, 2012 and ending on September 30, 2015	Sep. 30, 2000 Maximum	Dec. 31, 2012 Maximum	Dec. 31, 2011 Maximum	Dec. 31, 2012 Nonqualified Stock Options Minimum	Dec. 31, 2012 Nonqualified Stock Options Maximum	Dec. 12, 2012 Restricted Stock Units (RSUs)
Stock Based Compensation Activity [Line Items]
Unrecognized compensation costs related to non-vested awards	$ 4,800,000
Weighted average period for recognition of compensation costs related to non-vested awards	2 years 8 months 12 days
Performance Share Awards Fully Expensed	1,600,000
Weighted average per share fair value of stock options	$ 8.48	$ 5.24
Dividend yield	0.00%	0.00%
Stock option expiration term upon expiration of employment or service											7 years	10 years
Percentage of non-qualified stock options on each of first five anniversaries			20.00%
Percentage of non-qualified stock options on each of first four anniversaries				25.00%
Total pre-tax intrinsic value of options exercised									100,000
Restricted stock expenses		100,000							100,000
Expenses recognized related to Performance Shares	200,000	200,000
Performance Shares, time period	3 years
Performance period start date					Oct. 01, 2010	Oct. 01, 2011	Oct. 01, 2012
Performance period end date					Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2015
Shares vested upon the achievement of all or a portion of certain performance objectives during the performance period					68,533	62,497	38,042
Common stock authorized, shares								400,000
Annual compensation withheld								10.00%
Annual compensation withheld, maximum limit								25,000
Employee contributions									100,000	100,000
Stock compensation expenses recognized									100,000	100,000
Number of restricted stock units awarded													11,776
RSU award vest each year													33.00%
RSU expenses									$ 100,000