BUSINESS SEGMENTS - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 566,350	$ 549,633	$ 1,114,788	$ 1,060,155
United States
Disaggregation of Revenue [Line Items]
Revenue	445,543	431,569	878,794	832,607
Europe
Disaggregation of Revenue [Line Items]
Revenue	34,622	28,862	47,235	47,055
Canada
Disaggregation of Revenue [Line Items]
Revenue	29,591	28,887	61,199	61,862
Australia
Disaggregation of Revenue [Line Items]
Revenue	39,221	42,994	94,055	87,826
All other countries
Disaggregation of Revenue [Line Items]
Revenue	17,373	17,321	33,505	30,805
Consumer and Professional Products
Disaggregation of Revenue [Line Items]
Revenue	274,912	287,732	515,988	504,206
Consumer and Professional Products | United States
Disaggregation of Revenue [Line Items]
Revenue	191,412	204,445	351,570	347,361
Consumer and Professional Products | Europe
Disaggregation of Revenue [Line Items]
Revenue	24,737	20,343	31,342	28,208
Consumer and Professional Products | Canada
Disaggregation of Revenue [Line Items]
Revenue	17,515	18,845	35,296	38,210
Consumer and Professional Products | Australia
Disaggregation of Revenue [Line Items]
Revenue	39,032	41,749	93,260	85,788
Consumer and Professional Products | All other countries
Disaggregation of Revenue [Line Items]
Revenue	2,216	2,350	4,520	4,639
Consumer and Professional Products | Residential repair and remodel
Disaggregation of Revenue [Line Items]
Revenue	40,505	38,441	75,595	65,599
Consumer and Professional Products | Retail
Disaggregation of Revenue [Line Items]
Revenue	144,904	162,576	264,524	275,941
Consumer and Professional Products | Residential new construction
Disaggregation of Revenue [Line Items]
Revenue	14,884	13,545	29,857	27,817
Consumer and Professional Products | Industrial
Disaggregation of Revenue [Line Items]
Revenue	10,535	11,416	21,158	21,174
Consumer and Professional Products | International excluding North America
Disaggregation of Revenue [Line Items]
Revenue	64,084	61,754	124,854	113,675
Home and Building Products
Disaggregation of Revenue [Line Items]
Revenue	209,829	186,799	451,210	410,094
Home and Building Products | United States
Disaggregation of Revenue [Line Items]
Revenue	199,060	175,945	426,010	385,772
Home and Building Products | Europe
Disaggregation of Revenue [Line Items]
Revenue	5	29	28	46
Home and Building Products | Canada
Disaggregation of Revenue [Line Items]
Revenue	7,867	6,984	19,120	17,965
Home and Building Products | Australia
Disaggregation of Revenue [Line Items]
Revenue	0	266	0	450
Home and Building Products | All other countries
Disaggregation of Revenue [Line Items]
Revenue	2,897	3,575	6,052	5,861
Home and Building Products | Residential repair and remodel
Disaggregation of Revenue [Line Items]
Revenue	100,808	90,271	222,805	203,638
Home and Building Products | Commercial construction
Disaggregation of Revenue [Line Items]
Revenue	86,300	76,181	178,187	160,557
Home and Building Products | Residential new construction
Disaggregation of Revenue [Line Items]
Revenue	22,721	20,347	50,218	45,899
Defense Electronics
Disaggregation of Revenue [Line Items]
Revenue	81,609	75,102	147,590	145,855
Defense Electronics | United States
Disaggregation of Revenue [Line Items]
Revenue	55,071	51,179	101,214	99,474
Defense Electronics | Europe
Disaggregation of Revenue [Line Items]
Revenue	9,880	8,490	15,865	18,801
Defense Electronics | Canada
Disaggregation of Revenue [Line Items]
Revenue	4,209	3,058	6,783	5,687
Defense Electronics | Australia
Disaggregation of Revenue [Line Items]
Revenue	189	979	795	1,588
Defense Electronics | All other countries
Disaggregation of Revenue [Line Items]
Revenue	12,260	11,396	22,933	20,305
Defense Electronics | U.S. Government
Disaggregation of Revenue [Line Items]
Revenue	53,623	46,376	96,324	91,936
Defense Electronics | International
Disaggregation of Revenue [Line Items]
Revenue	25,021	23,129	43,554	45,228
Defense Electronics | Commercial
Disaggregation of Revenue [Line Items]
Revenue	$ 2,965	$ 5,597	$ 7,712	$ 8,691