CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-in- Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Sep. 30, 2012		34,839
Beginning Balance at Sep. 30, 2012	$ 474,406	$ 348	$ 1,103,611	$ (1,718,570)	$ 1,104,825	$ (15,808)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	25,850		25,850
Issuance of treasury stock under employee stock plans (in shares)		1,642
Issuance of treasury stock under employee stock plans	30,256	$ 17	(22,150)	52,389
Tax effect from share-based payment arrangements	2,887		2,887
Repurchases of common stock (shares)		(1,695)
Repurchases of common stock	(84,893)	$ (17)		(84,876)
Dividends paid	(2,824)				(2,824)
Net income	90,095				90,095
Foreign currency translation adjustments	(5,100)					(5,100)
Ending Balance (in shares) at Sep. 30, 2013		34,786
Ending Balance at Sep. 30, 2013	530,677	$ 348	1,110,198	(1,751,057)	1,192,096	(20,908)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	36,362		36,362
Issuance of treasury stock under employee stock plans (in shares)		911
Issuance of treasury stock under employee stock plans	6,554	$ 9	(23,278)	29,823
Tax effect from share-based payment arrangements	6,035		6,035
Repurchases of common stock (shares)		(3,650)
Repurchases of common stock	(214,898)	$ (37)		(214,861)
Dividends paid	(2,714)				(2,714)
Net income	94,879				94,879
Foreign currency translation adjustments	(2,281)					(2,281)
Ending Balance (in shares) at Sep. 30, 2014		32,047
Ending Balance at Sep. 30, 2014	454,614	$ 320	1,129,317	(1,936,095)	1,284,261	(23,189)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	45,308		45,308
Issuance of treasury stock under employee stock plans (in shares)		954
Issuance of treasury stock under employee stock plans	(1,203)	$ 10	(34,366)	33,153
Tax effect from share-based payment arrangements	12,530		12,530
Repurchases of common stock (shares)		(1,711)
Repurchases of common stock	(130,719)	$ (17)		(130,702)
Dividends paid	(2,508)				(2,508)
Net income	86,502				86,502
Foreign currency translation adjustments	(27,526)					(27,526)
Ending Balance (in shares) at Sep. 30, 2015		31,290
Ending Balance at Sep. 30, 2015	$ 436,998	$ 313	$ 1,152,789	$ (2,033,644)	$ 1,368,255	$ (50,715)