BUSINESS SEGMENTS - Segment EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 64,760	$ 69,456	$ 207,181	$ 172,579
Depreciation and amortization	(15,806)	(15,523)	(46,955)	(47,067)
Loss from debt extinguishment, net	0	(1,235)	0	(7,925)
Income before taxes	29,073	34,480	96,102	54,360
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	75,684	80,536	242,054	207,548
Depreciation and amortization	(15,657)	(15,370)	(46,606)	(46,611)
Operating Segments \| Consumer and Professional Products
Segment Reporting Information [Line Items]
Adjusted EBITDA	29,388	37,115	99,524	84,068
Depreciation and amortization	(8,781)	(8,197)	(25,600)	(24,650)
Operating Segments \| Home and Building Products
Segment Reporting Information [Line Items]
Adjusted EBITDA	42,156	39,299	130,585	110,635
Depreciation and amortization	(4,375)	(4,507)	(13,095)	(13,975)
Operating Segments \| Defense Electronics
Segment Reporting Information [Line Items]
Adjusted EBITDA	4,140	4,122	11,945	12,845
Depreciation and amortization	(2,501)	(2,666)	(7,911)	(7,986)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Unallocated Expenses	(10,924)	(11,080)	(34,873)	(34,969)
Net interest expense	(15,799)	(16,585)	(46,971)	(49,096)
Depreciation and amortization	(15,806)	(15,523)	(46,955)	(47,067)
Loss from debt extinguishment, net	0	(1,235)	0	(7,925)
Restructuring charges	(4,082)	(1,633)	(22,444)	(11,171)
Acquisition costs	0	0	0	2,960
Gain on sale of SEG business	$ 0	$ 0	$ 5,291	$ 0

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The capitalized costs incurred during the period (excluded from amortization) to purchase, lease or otherwise acquire an unproved property, including costs of lease bonuses and options to purchase or lease properties, the portion of costs applicable to minerals when land including mineral rights is purchased in fee, brokers' fees, recording fees, legal costs, and other costs incurred in acquiring properties.

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