Stock-based Compensation (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Nov. 30, 2011	Sep. 30, 2012 item	Sep. 30, 2011	Sep. 30, 2010
Original option plan August 2004
Information relating to stock options
Number of shares of common stock reserved for issuance		1,000,000
Second option plan January 2007
Information relating to stock options
Number of shares of common stock reserved for issuance		500,000
Stock Option Plans
Information relating to stock options
Number of plans		2
Number of shares of common stock reserved for issuance		1,500,000
Period during which options are exercisable		10 years
Vesting of awards per year (in percent)		33.33%
Award vesting period		3 years
Fair value assumptions
Fair Value (in dollars per share)	$ 23.91
Dividend Yield (as a percent)	1.58%
Risk-Free Interest Rate (as a percent)	0.40%
Expected Volatility (as a percent)	69.00%
Expected Life	3 years
Stock-based employee compensation expense		$ 561	$ 760	$ 1,021
Remaining unrecognized compensation expense		600
Weighted average period for recognition		1 year 1 month 28 days
Activity under stock option plans, number of shares
Outstanding at beginning of the period (in shares)		373,187
Granted (in shares)		23,200
Exercised (in shares)		(77,611)
Outstanding at end of the period (in shares)		318,776	373,187
Vested or expected to vest (in shares)		303,731
Exercisable at end of period (in shares)		266,636
Outstanding at end of period, Aggregate Intrinsic Value		4,041
Vested or expected to vest, Aggregate Intrinsic Value		4,041
Exercisable at end of the period, Aggregate Intrinsic Value		$ 3,624
Weighted Average Exercise Prices
Outstanding at beginning of the period (in dollars per share)		$ 38.53
Granted (in dollars per share)		$ 55.88
Exercised (in dollars per share)		$ 21.05
Outstanding at end of period (in dollars per share)		$ 44.05	$ 38.53
Vested or expected to vest (in dollars per share)		$ 44.05
Exercisable at end of the period (in dollars per share)		$ 43.70
Outstanding at end of the period, Weighted Average Remaining Contractual Life		5 years 5 months 26 days
Vested or expected to vest, Weighted Average Remaining Contractual Life		5 years 5 months 26 days
Exercisable at end of the period, Weighted Average Remaining Contractual Life		4 years 11 months 1 day
Stock Option Plans | Certain Employees
Activity under stock option plans, number of shares
Granted (in shares)	23,200
Stock Option Plans | Original option plan August 2004
Information relating to stock options
Number of shares of common stock reserved for issuance		1,000,000
Stock Option Plans | Second option plan January 2007
Information relating to stock options
Number of shares of common stock reserved for issuance		500,000