Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Cash Flow Hedging [Member]	Cash Flow Hedging [Member] Accumulated Other Comprehensive Loss [Member]	Net Investment Hedging [Member]	Net Investment Hedging [Member] Accumulated Other Comprehensive Loss [Member]
Beginning Balance, shares at Sep. 30, 2016		114,968
Beginning Balance, value at Sep. 30, 2016	$ 842,666	$ 1,150	$ 1,598,548	$ (657,079)	$ (99,953)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued for employee stock-based awards, shares		1,586
Common stock issued for employee stock-based awards, value	0	$ 15	(15)
Shares surrendered by employees to pay taxes related to stock-based awards, shares		(544)
Shares surrendered by employees to pay taxes related to stock-based awards, value	(26,654)	$ (5)	(26,649)
Compensation expense from stock-based awards	76,708		76,708
Common stock issued for employee stock purchase plan, shares		269
Common stock issued for employee stock purchase plan, value	10,778	$ 3	10,775
Excess tax benefits from stock-based awards	644		644
Net income (loss)	6,239			6,239
Repurchases of common stock, shares		(946)
Repurchases of common stock, value	(50,991)	$ (10)	(50,981)
Unrealized loss on cash flow hedges, net of tax	(299)					$ (299)	$ (299)
Foreign currency translation adjustment	16,593				16,593
Unrealized gain (loss) on marketable securities, net of tax	(22)				(22)
Change in pension benefits, net of tax	9,774				9,774
Ending Balance, shares at Sep. 30, 2017		115,333
Ending Balance, value at Sep. 30, 2017	885,436	$ 1,153	1,609,030	(650,840)	(73,907)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle | Accounting Standards Update 2016-09 [Member]	125		681	(556)
Common stock issued for employee stock-based awards, shares		1,830
Common stock issued for employee stock-based awards, value	0	$ 18	(18)
Shares surrendered by employees to pay taxes related to stock-based awards, shares		(664)
Shares surrendered by employees to pay taxes related to stock-based awards, value	(45,374)	$ (6)	(45,368)
Common stock issued, shares		10,582
Common stock issued, value	995,500	$ 106	995,394
Compensation expense from stock-based awards	82,939		82,939
Common stock issued for employee stock purchase plan, shares		292
Common stock issued for employee stock purchase plan, value	15,654	$ 2	15,652
Net income (loss)	51,987			51,987
Repurchases of common stock, shares		(9,392)
Repurchases of common stock, value	(1,100,000)	$ (93)	(1,099,907)
Unrealized loss on cash flow hedges, net of tax	1,928					1,928	1,928
Foreign currency translation adjustment	(11,767)				(11,767)
Unrealized gain (loss) on marketable securities, net of tax	(269)				(269)
Change in pension benefits, net of tax	$ (1,570)				(1,570)
Ending Balance, shares at Sep. 30, 2018	117,981	117,981
Ending Balance, value at Sep. 30, 2018	$ 874,589	$ 1,180	1,558,403	(599,409)	(85,585)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle | Accounting Standards Update 2016-16 [Member]	72,261			72,261
Cumulative effect of new accounting principle | Accounting Standards Update 2014-09 [Member]	363,218			363,218
Common stock issued for employee stock-based awards, shares		1,495
Common stock issued for employee stock-based awards, value	0	$ 15	(15)
Shares surrendered by employees to pay taxes related to stock-based awards, shares		(504)
Shares surrendered by employees to pay taxes related to stock-based awards, value	(44,366)	$ (5)	(44,361)
Common stock issued, value	(140)		(140)
Compensation expense from stock-based awards	86,400		86,400
Common stock issued for employee stock purchase plan, shares		275
Common stock issued for employee stock purchase plan, value	17,615	$ 3	17,612
Net income (loss)	(27,460)			(27,460)
Repurchases of common stock, shares		(4,348)
Repurchases of common stock, value	(114,994)	$ (44)	(114,950)
Unrealized loss on cash flow hedges, net of tax	4,702					$ (385)	$ (385)	$ 5,087	$ 5,087
Foreign currency translation adjustment	(24,755)				(24,755)
Unrealized gain (loss) on marketable securities, net of tax	530				530
Change in pension benefits, net of tax	$ (5,602)				(5,602)
Ending Balance, shares at Sep. 30, 2019	114,899	114,899
Ending Balance, value at Sep. 30, 2019	$ 1,201,998	$ 1,149	$ 1,502,949	$ (191,390)	$ (110,710)