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, 2013		34,786
Beginning 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 (in 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 (in 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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	55,509		55,509
Issuance of treasury stock under employee stock plans (in shares)		980
Issuance of treasury stock under employee stock plans	(12,127)	$ 10	(47,406)	35,269
Tax effect from share-based payment arrangements	24,184		24,184
Repurchases of common stock (in shares)		(1,335)
Repurchases of common stock	(138,399)	$ (14)		(138,385)
Dividends paid	(2,489)				(2,489)
Net income	109,448				109,448
Foreign currency translation adjustments	(26,296)					(26,296)
Ending Balance (in shares) at Sep. 30, 2016		30,935
Ending Balance at Sep. 30, 2016	$ 446,828	$ 309	$ 1,185,076	$ (2,136,760)	$ 1,475,214	$ (77,011)