Stock Based Compensation (Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at end of period (shares)	5,621,000
Common shares reserved under stock option plans
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period (shares)	5,477,000	4,851,000	4,275,000
Granted (shares)	1,106,000	1,608,000	1,194,000
Exercised (shares)	(1,116,000)	(857,000)	(524,000)
Cancelled/Expired (shares)	(116,000)	(125,000)	(94,000)
Outstanding at end of period (shares)	5,351,000	5,477,000	4,851,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted-Average Exercise Price, Outstanding at beginning of period	$ 6.81	$ 5.57	$ 4.77
Weighted-Average Exercise Price, Granted	$ 9.31	$ 9.91	$ 8.29
Weighted-Average Exercise Price, Exercised	$ 5.61	$ 5.18	$ 4.09
Weighted-Average Exercise Price, Cancelled/Expired	$ 9.83	$ 9.68	$ 12.01
Weighted-Average Exercise Price, Outstanding at end of period	$ 7.51	$ 6.81	$ 5.57
Weighted-Average Remaining Contractual Term in Years, Outstanding at September 30, 2012 (years)	4 years 2 months 1 day
Aggregate Intrinsic Value, Outstanding at September 30, 2013	$ 18,127
Number of Shares, Exercisable (shares)	3,173,000	3,072,000	2,868,000
Weighted-Average Exercise Price, Exercisable	$ 6.25	$ 5.42	$ 5.31
Weighted-Average Remaining Contractual Term in Years, Exercisable (years)	3 years 2 months 23 days	3 years 3 months 11 days	3 years 6 months 4 days
Aggregate Intrinsic Value, Exercisable at September 30, 2013	14,738
Number of Shares, Vested and expected to vest after September 30, 2013 (shares)	5,245,000
Weighted-Average Exercise Price, Vested and expected to vest after September 30, 2013	$ 7.47
Weighted-Average Remaining Contractual Term in Years, Vested and expected to vest after September 30, 2013 (years)	4 years 1 month 21 days
Aggregate Intrinsic Value, Vested and expected to vest after September 30, 2013	$ 17,985