BUSINESS SEGMENTS - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 634,832	$ 566,350	$ 1,244,123	$ 1,114,788
United States
Disaggregation of Revenue [Line Items]
Revenue	470,489	445,543	937,840	878,794
Europe
Disaggregation of Revenue [Line Items]
Revenue	44,797	34,622	64,858	47,235
Canada
Disaggregation of Revenue [Line Items]
Revenue	33,500	29,591	68,932	61,199
Australia
Disaggregation of Revenue [Line Items]
Revenue	63,813	39,221	133,672	94,055
All other countries
Disaggregation of Revenue [Line Items]
Revenue	22,233	17,373	38,821	33,505
Consumer and Professional Products
Disaggregation of Revenue [Line Items]
Revenue	331,871	274,912	622,913	515,988
Consumer and Professional Products | United States
Disaggregation of Revenue [Line Items]
Revenue	205,368	191,412	388,810	351,570
Consumer and Professional Products | Europe
Disaggregation of Revenue [Line Items]
Revenue	38,965	24,737	52,121	31,342
Consumer and Professional Products | Canada
Disaggregation of Revenue [Line Items]
Revenue	21,778	17,515	43,893	35,296
Consumer and Professional Products | Australia
Disaggregation of Revenue [Line Items]
Revenue	63,691	39,032	133,231	93,260
Consumer and Professional Products | All other countries
Disaggregation of Revenue [Line Items]
Revenue	2,069	2,216	4,858	4,520
Consumer and Professional Products | Residential repair and remodel
Disaggregation of Revenue [Line Items]
Revenue	50,560	40,505	96,160	75,595
Consumer and Professional Products | Retail
Disaggregation of Revenue [Line Items]
Revenue	153,746	144,904	292,994	264,524
Consumer and Professional Products | Residential new construction
Disaggregation of Revenue [Line Items]
Revenue	14,540	14,884	28,055	29,857
Consumer and Professional Products | Industrial
Disaggregation of Revenue [Line Items]
Revenue	9,958	10,535	19,489	21,158
Consumer and Professional Products | International excluding North America
Disaggregation of Revenue [Line Items]
Revenue	103,067	64,084	186,215	124,854
Home and Building Products
Disaggregation of Revenue [Line Items]
Revenue	242,811	209,829	493,292	451,210
Home and Building Products | United States
Disaggregation of Revenue [Line Items]
Revenue	230,955	199,060	467,486	426,010
Home and Building Products | Europe
Disaggregation of Revenue [Line Items]
Revenue	41	5	41	28
Home and Building Products | Canada
Disaggregation of Revenue [Line Items]
Revenue	9,797	7,867	21,285	19,120
Home and Building Products | Australia
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Home and Building Products | All other countries
Disaggregation of Revenue [Line Items]
Revenue	2,018	2,897	4,480	6,052
Home and Building Products | Residential repair and remodel
Disaggregation of Revenue [Line Items]
Revenue	120,827	100,808	246,942	222,805
Home and Building Products | Residential new construction
Disaggregation of Revenue [Line Items]
Revenue	27,233	22,721	55,660	50,218
Home and Building Products | Commercial construction
Disaggregation of Revenue [Line Items]
Revenue	94,751	86,300	190,690	178,187
Defense Electronics
Disaggregation of Revenue [Line Items]
Revenue	60,150	81,609	127,918	147,590
Defense Electronics | United States
Disaggregation of Revenue [Line Items]
Revenue	34,166	55,071	81,544	101,214
Defense Electronics | Europe
Disaggregation of Revenue [Line Items]
Revenue	5,791	9,880	12,696	15,865
Defense Electronics | Canada
Disaggregation of Revenue [Line Items]
Revenue	1,925	4,209	3,754	6,783
Defense Electronics | Australia
Disaggregation of Revenue [Line Items]
Revenue	122	189	441	795
Defense Electronics | All other countries
Disaggregation of Revenue [Line Items]
Revenue	18,146	12,260	29,483	22,933
Defense Electronics | U.S. Government
Disaggregation of Revenue [Line Items]
Revenue	35,045	53,623	82,369	96,324
Defense Electronics | International
Disaggregation of Revenue [Line Items]
Revenue	21,497	25,021	38,392	43,554
Defense Electronics | Commercial
Disaggregation of Revenue [Line Items]
Revenue	$ 3,608	$ 2,965	$ 7,157	$ 7,712