Significant Accounting Policies - Earnings Per Share (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 03, 2020	Jul. 04, 2020	Apr. 04, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Oct. 03, 2020	Sep. 28, 2019	Sep. 29, 2018
Earnings Per Share [Abstract]
Weighted average shares outstanding—basic (in shares)									24,105,000	24,118,000	24,572,000
Dilutive effect of employee stock awards (in shares)									0	161,000	279,000
Weighted average shares outstanding—diluted (in shares)									24,105,000	24,279,000	24,851,000
Net income (loss) from continuing operations									$ (414,139)	$ 53,825	$ 247,360
Loss from discontinued operations, net of income taxes									0	0	(2)
Net income (loss)	$ 7,689	$ (8,708)	$ (418,913)	$ 5,793	$ 624	$ (3,099)	$ 20,750	$ 35,550	$ (414,139)	$ 53,825	$ 247,358
Dilutive securities excluded from calculation of dilutive shares (in shares)										98,103	103,547