Consolidated Statement of Stockholder's Equity Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Cash Flow Hedging	Cash Flow Hedging Accumulated Other Comprehensive Loss	Net Investment Hedging	Net Investment Hedging Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Sep. 30, 2018		117,981,000
Beginning balance at Sep. 30, 2018	$ 874,589	$ 1,180	$ 1,558,403	$ (599,409)	$ (85,585)
Common stock issued for employee stock-based awards (in shares)		1,108,000
Common stock issued for employee stock-based awards	0	$ 11	(11)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(388,000)
Shares surrendered by employees to pay taxes related to stock-based awards	(34,491)	$ (4)	(34,487)
Common stock issued	(140)		(140)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		122,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	8,798	$ 1	8,797
Compensation expense from stock-based awards	56,374		56,374
Net income (loss)	(22,528)			(22,528)
Stock Repurchased and Retired During Period, Shares		(725,000)
Stock Repurchased and Retired During Period, Value	(64,994)	$ (7)	(64,987)
Unrealized loss on hedging instruments	277					$ (385)	$ (385)	$ 662	$ 662
Foreign currency translation adjustment	(11,602)				(11,602)
Unrealized loss on available-for-sale securities, net of tax	302				302
Change in pension benefits, net of tax	1,484				1,484
Ending balance (in shares) at Mar. 30, 2019		118,098,000
Ending balance at Mar. 30, 2019	1,247,708	$ 1,181	1,523,949	(182,298)	(95,124)
Beginning balance (in shares) at Dec. 29, 2018		118,657,000
Beginning balance at Dec. 29, 2018	1,321,169	$ 1,187	1,553,875	(138,785)	(95,108)
Common stock issued for employee stock-based awards (in shares)		52,000
Common stock issued for employee stock-based awards	0	$ 0	0
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(8,000)
Shares surrendered by employees to pay taxes related to stock-based awards	(703)	$ 0	(703)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		122,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	8,798	$ 1	8,797
Compensation expense from stock-based awards	26,967		26,967
Net income (loss)	(43,513)			(43,513)
Stock Repurchased and Retired During Period, Shares		(725,000)
Stock Repurchased and Retired During Period, Value	(64,994)	$ (7)	(64,987)
Unrealized loss on hedging instruments	2,955							2,955	2,955
Foreign currency translation adjustment	(4,033)				(4,033)
Unrealized loss on available-for-sale securities, net of tax	289				289
Change in pension benefits, net of tax	773				773
Ending balance (in shares) at Mar. 30, 2019		118,098,000
Ending balance at Mar. 30, 2019	$ 1,247,708	$ 1,181	1,523,949	(182,298)	(95,124)
Beginning balance (in shares) at Sep. 30, 2019	114,899,000	114,899,000
Beginning balance at Sep. 30, 2019	$ 1,201,998	$ 1,149	1,502,949	(191,390)	(110,710)
Common stock issued for employee stock-based awards (in shares)		958,000
Common stock issued for employee stock-based awards	0	$ 10	(10)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(318,000)
Shares surrendered by employees to pay taxes related to stock-based awards	(23,571)	$ (3)	(23,568)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		156,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	8,980	$ 1	8,979
Compensation expense from stock-based awards	48,420		48,420
Net income (loss)	42,611			42,611
Stock Repurchased During Period, Value	65,000
Unrealized loss on hedging instruments	(2,642)							(2,642)	(2,642)
Foreign currency translation adjustment	(412)				(412)
Unrealized loss on available-for-sale securities, net of tax	(544)				(544)
Change in pension benefits, net of tax	$ 813				813
Ending balance (in shares) at Mar. 28, 2020	115,695,000	115,695,000
Ending balance at Mar. 28, 2020	$ 1,274,081	$ 1,157	1,536,770	(150,351)	(113,495)
Beginning balance (in shares) at Dec. 28, 2019		115,494,000
Beginning balance at Dec. 28, 2019	1,247,817	$ 1,155	1,508,030	(157,507)	(103,861)
Common stock issued for employee stock-based awards (in shares)		55,000
Common stock issued for employee stock-based awards	0	$ 1	(1)
Shares surrendered by employees to pay taxes related to stock-based awards (in shares)		(10,000)
Shares surrendered by employees to pay taxes related to stock-based awards	(722)	$ 0	(722)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		156,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	8,980	$ 1	8,979
Compensation expense from stock-based awards	20,484		20,484
Net income (loss)	7,156			7,156
Unrealized loss on hedging instruments	701							$ 701	$ 701
Foreign currency translation adjustment	(10,559)				(10,559)
Unrealized loss on available-for-sale securities, net of tax	(537)				(537)
Change in pension benefits, net of tax	$ 761				761
Ending balance (in shares) at Mar. 28, 2020	115,695,000	115,695,000
Ending balance at Mar. 28, 2020	$ 1,274,081	$ 1,157	$ 1,536,770	$ (150,351)	$ (113,495)