BUSINESS SEGMENTS - Segment EBITDA (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Segment adjusted EBITDA		$ 58,764	$ 39,918	$ 146,206	$ 119,184
Net interest expense		(15,796)	(12,662)	(48,482)	(38,656)
Segment depreciation and amortization		14,047	12,221	40,318	36,356
Unallocated amounts		12,016	10,613	32,993	31,379
Acquisition costs		3,598	0	7,597	0
Secondary equity offering costs		(1,205)	0	(1,205)	0
Income before taxes from continuing operations	$ 13,715
Income (loss) before taxes from continuing operations		9,002	4,547	10,117	13,147
Home And Building Products [Member]
Segment Reporting Information [Line Items]
Segment adjusted EBITDA		50,004	33,134	129,250	92,506
Segment depreciation and amortization		11,251	9,426	31,888	27,845
Telephonics [Member]
Segment Reporting Information [Line Items]
Segment adjusted EBITDA		8,760	6,784	16,956	26,678
Segment depreciation and amortization		2,676	2,670	8,090	8,157
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Special Dividend ESOP Charges		(3,220)	0	(3,220)	0
Secondary equity offering costs		(1,205)		(1,205)
Continuing Operations [Member] | Postretirement Life Insurance [Member]
Segment Reporting Information [Line Items]
Net interest expense		(15,796)	(12,662)	(48,482)	(38,656)
Unallocated amounts		12,016	10,613	32,993	31,379
Income before taxes from continuing operations		0	0	(2,614)	0
Income (loss) before taxes from continuing operations		$ 9,002	$ 4,547	$ 10,117	$ 13,147