BUSINESS SEGMENTS - Segment EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 67,781	$ 47,963	$ 142,421	$ 103,123
Depreciation and amortization	(15,883)	(15,719)	(31,149)	(31,544)
Loss from debt extinguishment, net	0	(6,690)	0	(6,690)
Income before taxes	27,860	2,929	67,029	19,880
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	79,703	59,910	166,370	127,012
Depreciation and amortization	(15,733)	(15,566)	(30,949)	(31,241)
Operating Segments | Consumer and Professional Products
Segment Reporting Information [Line Items]
Adjusted EBITDA	37,423	25,027	70,136	46,953
Depreciation and amortization	(8,620)	(8,222)	(16,819)	(16,453)
Operating Segments | Home and Building Products
Segment Reporting Information [Line Items]
Adjusted EBITDA	40,060	30,635	88,429	71,336
Depreciation and amortization	(4,379)	(4,668)	(8,720)	(9,468)
Operating Segments | Defense Electronics
Segment Reporting Information [Line Items]
Adjusted EBITDA	2,220	4,248	7,805	8,723
Depreciation and amortization	(2,734)	(2,676)	(5,410)	(5,320)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Unallocated Expenses	(11,922)	(11,947)	(23,949)	(23,889)
Net interest expense	(15,527)	(16,561)	(31,172)	(32,511)
Depreciation and amortization	(15,883)	(15,719)	(31,149)	(31,544)
Loss from debt extinguishment, net	0	(6,690)	0	(6,690)
Restructuring charges	(7,562)	(3,104)	(18,362)	(9,538)
Acquisition costs	0	2,960	0	2,960
Gain (adjustment) on sale of SEG business	$ (949)	$ 0	$ 5,291	$ 0