ACQUISITIONS - Summary of Level 3 Fair Values Assigned to Net Assets Acquired and Liabilities Assumed As of Acquisition Date (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2018
Fair value of assets acquired and liabilities assumed:
Excess purchase price attributed to goodwill acquired	$ 186,231	$ 188,239	$ 170,129
Vergokan
Fair value of consideration transferred:
Cash consideration	58,728
Other liability consideration	0
Total consideration transferred	58,728
Fair value of assets acquired and liabilities assumed:
Cash	829
Accounts receivable	8,761
Inventories	11,434
Intangible assets	12,621
Fixed assets	32,490
Accounts payable	(18,716)
Gain on purchase of business	0
Other	1,680
Net assets acquired	49,099
Excess purchase price attributed to goodwill acquired	9,629
Other
Fair value of consideration transferred:
Cash consideration	41,641
Other liability consideration	1,400
Total consideration transferred	43,041
Fair value of assets acquired and liabilities assumed:
Cash	1,541
Accounts receivable	8,217
Inventories	7,494
Intangible assets	16,400
Fixed assets	19,298
Accounts payable	(7,608)
Gain on purchase of business	(7,384)
Other	(3,412)
Net assets acquired	34,546
Excess purchase price attributed to goodwill acquired	8,495
Acquisitions For Fiscal Year 2019
Fair value of consideration transferred:
Cash consideration	100,369
Other liability consideration	1,400
Total consideration transferred	101,769
Fair value of assets acquired and liabilities assumed:
Cash	2,370
Accounts receivable	16,978
Inventories	18,928
Intangible assets	29,021
Fixed assets	51,788
Accounts payable	(26,324)
Gain on purchase of business	(7,384)
Other	(1,732)
Net assets acquired	83,645
Excess purchase price attributed to goodwill acquired	$ 18,124