Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Debt Instrument [Line Items]
Total debt	$ 976,900	$ 977,155
Less unamortized discount and lender fees	(11,623)	(12,138)
Total net debt	965,277	965,017
Current portion of debt	(113,707)	(13,418)
Total long‑term debt	851,570	951,599
First Lien Term Facility, due December 20, 2024
Debt Instrument [Line Items]
Total debt	926,384	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	759	807
Equipment Financings \| Equipment Financing, due June 30, 2024 to July 5, 2029
Debt Instrument [Line Items]
Total debt	48,096	45,960
MAGENTO \| Facility Financing \| Mortgage, due June 30, 2028
Debt Instrument [Line Items]
Total debt	$ 1,661	$ 1,635

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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