BUSINESS SEGMENTS - Revenues (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($) segment	Mar. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenue	$ 634,832	$ 566,350	$ 1,244,123	$ 1,114,788
Consumer and Professional Products
Segment Reporting Information [Line Items]
Revenue	331,871	274,912	622,913	515,988
Home and Building Products
Segment Reporting Information [Line Items]
Revenue	242,811	209,829	493,292	451,210
Defense Electronics
Segment Reporting Information [Line Items]
Revenue	$ 60,150	$ 81,609	$ 127,918	$ 147,590