Condensed Consolidated Statements of Stockholder's Equity Statement - USD ($) shares in Thousands, $ in Thousands		Total	Number of Common Shares	Common Stock and Additional Paid in Capital	Treasury Stock	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance at Sep. 30, 2017		$ 1,647,684		$ 6,185,088	$ (633,740)	$ 76,794	$ (3,980,458)
Common Stock, Shares, Issued at Sep. 30, 2017			101,672
Treasury Stock, Shares at Sep. 30, 2017					(30,008)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under stock plans			893
Issuances under stock plans, Value		2,526		2,526
Stock-based compensation		8,679		8,679
Repurchases of Treasury Stock, Shares					(1,323)
Repurchases of Treasury Stock, Value		(45,485)			$ (45,485)
Other comprehensive income (loss)		(175)				(175)
Net income (loss)		(154,910)					(154,910)
Common Stock, Shares, Issued at Dec. 30, 2017			102,565
Treasury Stock, Shares at Dec. 30, 2017					(31,331)
Balance at Dec. 30, 2017		1,501,588		6,196,293	$ (679,225)	76,619	(4,092,099)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting pronouncement (1)		43,269
Cumulative effect of new accounting pronouncement (1) | Accounting Standards Update 2016-09 [Member]	[1]						43,269
Balance at Sep. 29, 2018		1,472,844		6,222,988	$ (791,366)	73,944	(4,032,722)
Common Stock, Shares, Issued at Sep. 29, 2018			103,128
Treasury Stock, Shares at Sep. 29, 2018					(35,351)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances under stock plans			1,028
Issuances under stock plans, Value		3,568		3,568
Stock-based compensation		5,816		5,816
Repurchases of Treasury Stock, Shares					(449)
Repurchases of Treasury Stock, Value		(11,842)			$ (11,842)
Other comprehensive income (loss)		(3,851)				(3,851)
Net income (loss)		37,952					37,952
Common Stock, Shares, Issued at Dec. 29, 2018			104,156
Treasury Stock, Shares at Dec. 29, 2018					(35,800)
Balance at Dec. 29, 2018		1,532,617		$ 6,232,372	$ (803,208)	$ 70,093	(3,966,640)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting pronouncement (1)		$ 28,130
Cumulative effect of new accounting pronouncement (1) | Accounting Standards Update 2014-09 [Member]	[2]						$ 28,130

[1] (2)Due to the adoption of ASU 2016-09 "Improvements to Employee Share-Based Payment Accounting (Topic 718)".

[2] (1)Due to the adoption of ASU 2014-09 "Revenue from Contracts with Customers (Topic 606)" using the modified retrospective approach.