Fair Value of Financial Instruments - Summary of Fair Value of Financial Assets and Liabilities Measured on a Recurring Basis (Detail) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:		$ 12,274
Other long-term assets:
Other long-term assets:	$ 34,821	27,267
Accrued expenses:
Accrued expenses:	7,892	14,688
Other long-term liabilities:
Other long-term liabilities:	22,540	40,895
Level 1
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	0	0
Other long-term assets:
Other long-term assets:	0	0
Accrued expenses:
Accrued expenses:	0	0
Other long-term liabilities:
Other long-term liabilities:	0	0
Level 2
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	8,717	12,274
Other long-term assets:
Other long-term assets:	34,821	27,267
Accrued expenses:
Accrued expenses:	7,892	14,688
Other long-term liabilities:
Other long-term liabilities:	22,136	40,392
Level 3
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	0	0
Other long-term assets:
Other long-term assets:	0	0
Accrued expenses:
Accrued expenses:	0	0
Other long-term liabilities:
Other long-term liabilities:	404	503
Foreign currency forward contracts
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	1,468	134
Foreign currency forward contracts | Level 1
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:		0
Foreign currency forward contracts | Level 2
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:		134
Foreign currency forward contracts | Level 3
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:		0
Commodity index contracts
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	7,249	3,378
Commodity index contracts | Level 1
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	0	0
Commodity index contracts | Level 2
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	1,468	3,378
Commodity index contracts | Level 3
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	0	0
Interest rate swap contracts
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	8,717	8,762
Other long-term assets:
Other long-term assets:	34,821	27,267
Accrued expenses:
Accrued expenses:	7,892	14,688
Other long-term liabilities:
Other long-term liabilities:	22,136	40,392
Interest rate swap contracts | Level 1
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	0	0
Other long-term assets:
Other long-term assets:	0	0
Accrued expenses:
Accrued expenses:	0	0
Other long-term liabilities:
Other long-term liabilities:	0	0
Interest rate swap contracts | Level 2
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	7,249	8,762
Other long-term assets:
Other long-term assets:	34,821	27,267
Accrued expenses:
Accrued expenses:	7,892	14,688
Other long-term liabilities:
Other long-term liabilities:	22,136	40,392
Interest rate swap contracts | Level 3
Prepaid expenses and other current assets:
Prepaid expenses and other current assets:	0	0
Other long-term assets:
Other long-term assets:	0	0
Accrued expenses:
Accrued expenses:	0	0
Other long-term liabilities:
Other long-term liabilities:	0	0
Contingent consideration
Other long-term liabilities:
Other long-term liabilities:	404	503
Contingent consideration | Level 1
Other long-term liabilities:
Other long-term liabilities:	0	0
Contingent consideration | Level 2
Other long-term liabilities:
Other long-term liabilities:	0	0
Contingent consideration | Level 3
Other long-term liabilities:
Other long-term liabilities:	$ 404	$ 503