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Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Jan. 31, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Total debt	$ 879,927		$ 977,155
Less unamortized discount and lender fees	(9,957)		(12,138)
Total net debt	869,970		965,017
Current portion of debt	(14,611)		(13,418)
Total long‑term debt	855,359		951,599
First Lien Term Facility, due December 20, 2024
Debt Instrument [Line Items]
Total debt	821,646	$ 826,000	928,753
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt	0		0
Notes Payable, due July 31, 2023
Debt Instrument [Line Items]
Total debt	661		807
Equipment Financings \| Equipment Financing, due June 30, 2024 to July 5, 2029, interest rates ranging from 3.84% to 8.07%
Debt Instrument [Line Items]
Total debt	56,003		45,960
MAGENTO \| Facility Financing \| Mortgage, due June 30, 2028
Debt Instrument [Line Items]
Total debt	$ 1,617		$ 1,635
Minimum \| Equipment Financings \| Equipment Financing, due June 30, 2024 to July 5, 2029, interest rates ranging from 3.84% to 8.07%
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.84%
Maximum \| Equipment Financings \| Equipment Financing, due June 30, 2024 to July 5, 2029, interest rates ranging from 3.84% to 8.07%
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.07%