Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2021		Apr. 01, 2021	Mar. 31, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Total debt	$ 801,861				$ 885,470
Less unamortized deferred financing fees	(12,217)		$ (2,375)		(9,436)
Total net debt	789,644				876,034
Current portion of debt	(11,474)				(14,339)
Total long‑term debt	778,170				861,695
2021 Revolving Credit Facility, due April 2026
Debt Instrument [Line Items]
Total debt	95,000				0
First Lien Term Facility, due December 20, 2024
Debt Instrument [Line Items]
Total debt	0				819,276
Revolving Credit Facility
Debt Instrument [Line Items]
Total debt	0	[1]			0
Securitization Facility, due April 1, 2024
Debt Instrument [Line Items]
Total debt	148,151				0
Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% | Equipment Financings
Debt Instrument [Line Items]
Total debt	83,255				63,918
Notes Payable, due July 31, 2023
Debt Instrument [Line Items]
Total debt	455				611
Mortgages | Facility Financing | MAGENTO
Debt Instrument [Line Items]
Total debt	0	[2]			1,665
2021 Term Loan
Debt Instrument [Line Items]
Total debt	$ 475,000			$ 814,538	$ 0
Minimum | Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% | Equipment Financings
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.13%
Maximum | Equipment Financing, due September 30, 2023 to July 5, 2029, interest rates ranging from 3.13% to 8.07% | Equipment Financings
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	8.07%

[1] On April 1, 2021, the Company paid off the outstanding balance of the 2014 Term Loan (as defined below) and entered into the 2021 Credit Agreement (as defined below).

[2] In November 2020, the Company paid off the outstanding balance of the mortgage due June 30, 2028.