Leases - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
		Jun. 26, 2020	Jun. 26, 2020	Mar. 27, 2020	Dec. 27, 2019	Oct. 01, 2019	Sep. 30, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets		$ 37,068	$ 37,068
Operating lease, liability		38,221	38,221
Stockholders' equity		324,195	324,195	$ 295,434	$ 272,131		$ 232,936	$ 202,518	$ 158,497	$ 124,155	$ 122,059
Lease, cost		4,813	12,888
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity	[1]						(1,053)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets						$ 45,519
Operating lease, liability						46,941
Cost of sales
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease, cost		4,464	10,414
Selling, General and Administrative Expenses
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Lease, cost		349	2,474
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity		$ (118,395)	$ (118,395)	$ (142,473)	$ (166,659)		(200,396)	$ (246,393)	$ (282,943)	$ (314,831)	$ (317,373)
Accumulated Deficit | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity	[1]						$ (1,053)
Accumulated Deficit | Accounting Standards Update 2016-02 | Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity						$ 1,053

[1] Due to the adoption of ASU 2016-02