Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2020		Dec. 30, 2020	Sep. 30, 2020
Debt Instrument [Line Items]
Total debt	$ 887,552			$ 885,470
Less unamortized deferred financing fees	(8,911)			(9,436)
Total net debt	878,641			876,034
Current portion of debt	(18,426)			(14,339)
Total long‑term debt	860,215			861,695
First Lien Term Facility, due December 20, 2024
Debt Instrument [Line Items]
Total debt	816,907			819,276
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt	0			0
Notes Payable, due July 31, 2023
Debt Instrument [Line Items]
Total debt	560			611
Equipment Financings | Equipment Financing, due February 28, 2021 to July 5, 2029, interest rates ranging from 3.25% to 8.07% (1)
Debt Instrument [Line Items]
Total debt	$ 70,085	[1]		63,918
December 31 Equipment Financing [Member] | Equipment Financing, due February 28, 2021 to July 5, 2029, interest rates ranging from 3.25% to 8.07% (1)
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.25%
Total debt	$ 3,899
Dec 30 Equipment Financing [Member] | Equipment Financing, due February 28, 2021 to July 5, 2029, interest rates ranging from 3.25% to 8.07% (1)
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			3.73%
Total debt			$ 3,905
MAGENTO | Facility Financing | Mortgage (2)
Debt Instrument [Line Items]
Total debt	$ 0	[2]		$ 1,665
Minimum | Equipment Financings | Equipment Financing, due February 28, 2021 to July 5, 2029, interest rates ranging from 3.25% to 8.07% (1)
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.25%
Maximum | Equipment Financings | Equipment Financing, due February 28, 2021 to July 5, 2029, interest rates ranging from 3.25% to 8.07% (1)
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.07%

[1] On December 30, 2020, the Company completed $3,905 of equipment financings due December 30, 2027 at a fixed interest rate of 3.73%. On December 31, 2020, the Company completed $3,899 of equipment financings due February 28, 2021 at a fixed interest rate of 3.25%.

[2] During the three months ended December 31, 2020, the Company paid off the outstanding balance of the mortgage due June 30, 2028.