Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Accumulated Other Comprehensive Income	Additional Paid-in Capital	Accumulated Deficit
Treasury Stock, Shares			(23)
Balance at beginning of period, (in shares) at Sep. 28, 2018		65,202
Balance at beginning of period at Sep. 28, 2018	$ 668,675	$ 65	$ (330)	$ 2,188	$ 1,074,728	$ (407,976)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises (in shares)		12
Stock options exercises	24				24
Vesting of restricted common stock and units (in shares)		545
Vesting of restricted common stock and units	1	$ 1
Issuance of common stock pursuant to employee stock purchase plan (in shares)		156
Issuance of common stock pursuant to employee stock purchase plan	2,392				2,392
Shares repurchased for stock withholdings on restricted stock awards (in shares)		(192)
Shares repurchased for tax withholdings on equity awards	(3,426)				(3,426)
Share-based compensation	17,349				17,349
Other comprehensive loss, net of tax	1,610			1,610
Net loss	(69,600)					(69,600)
Balance at end of period, (in shares) at Mar. 29, 2019		65,723
Balance at end of period at Mar. 29, 2019	617,025	$ 66	$ (330)	3,798	1,091,067	(477,576)
Treasury Stock, Shares			(23)
Balance at beginning of period, (in shares) at Dec. 28, 2018		65,395
Balance at beginning of period at Dec. 28, 2018	657,256	$ 65	$ (330)	2,841	1,086,052	(431,372)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises (in shares)		12
Stock options exercises					24
Vesting of restricted common stock and units (in shares)		490
Vesting of restricted common stock and units		$ 1
Shares repurchased for stock withholdings on restricted stock awards (in shares)		(174)
Shares repurchased for tax withholdings on equity awards	(3,085)				(3,085)
Share-based compensation	8,076				8,076
Other comprehensive loss, net of tax	957			957
Net loss	(46,204)					(46,204)
Balance at end of period, (in shares) at Mar. 29, 2019		65,723
Balance at end of period at Mar. 29, 2019	617,025	$ 66	$ (330)	3,798	1,091,067	(477,576)
Treasury Stock, Shares			(23)
Treasury Stock, Shares			(23)
Balance at beginning of period, (in shares) at Sep. 27, 2019		66,177
Balance at beginning of period at Sep. 27, 2019	$ 313,896	$ 66	$ (330)	4,358	1,101,576	(791,774)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises (in shares)	18	18
Stock options exercises	$ 122				122
Vesting of restricted common stock and units (in shares)		564
Vesting of restricted common stock and units	1	$ 1
Issuance of common stock pursuant to employee stock purchase plan (in shares)		160
Issuance of common stock pursuant to employee stock purchase plan	1,930				1,930
Shares repurchased for stock withholdings on restricted stock awards (in shares)		(201)
Shares repurchased for tax withholdings on equity awards	(5,949)				(5,949)
Share-based compensation	18,426				18,426
Other comprehensive loss, net of tax	(2,232)			(2,232)
Net loss	(38,588)					(38,588)
Balance at end of period, (in shares) at Apr. 03, 2020		66,718
Balance at end of period at Apr. 03, 2020	285,731	$ 67	$ (330)	2,126	1,116,105	(832,237)
Treasury Stock, Shares			(23)
Balance at beginning of period, (in shares) at Jan. 03, 2020		66,346
Balance at beginning of period at Jan. 03, 2020	293,520	$ 66	$ (330)	4,189	1,111,606	(822,011)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises (in shares)		16
Stock options exercises	79				79
Vesting of restricted common stock and units (in shares)		554
Vesting of restricted common stock and units	1	$ 1
Shares repurchased for stock withholdings on restricted stock awards (in shares)		(198)
Shares repurchased for tax withholdings on equity awards	(5,856)				(5,856)
Share-based compensation	10,276				10,276
Other comprehensive loss, net of tax	(2,063)			(2,063)
Net loss	(10,226)					(10,226)
Balance at end of period, (in shares) at Apr. 03, 2020		66,718
Balance at end of period at Apr. 03, 2020	285,731	$ 67	$ (330)	$ 2,126	$ 1,116,105	(832,237)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ (1,875)					$ (1,875)
Treasury Stock, Shares			(23)