Equity Award Plans - Additional Information (Details) (USD $)	3 Months Ended
	Dec. 31, 2013 Executives	Dec. 31, 2012	Dec. 31, 2011
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Number of executive officers granted performance based RSU	4
Cumulative operating income during performance period, minimum	$ 124,110,000	$ 109,582,000	$ 120,000,000
Cumulative operating income during performance period, maximum	149,728,000	132,201,000	132,000,000
Exercise of stock options, shares	146,899	85,949
Aggregate exercise price	1,617,000	618,000
Net-share settled by company	51,188	30,996
Repurchase of common stock, shares	52,130	26,624
Payments for tax obligation to the tax authorities on exercise or vesting date	$ 1,657,000	$ 532,000
Minimum | Executives | RSUs
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Cumulative restricted stock units available for future declaration	15,113	18,541	19,531
Maximum | Executives | RSUs
Deferred Compensation Arrangement With Individual Share Based Payments [Line Items]
Cumulative restricted stock units available for future declaration	45,337	55,621	58,590