RESTRUCTURING CHARGES - Narrative (Details) $ in Thousands			3 Months Ended				9 Months Ended		12 Months Ended
	Nov. 12, 2020 USD ($)	Sep. 30, 2020 USD ($) position	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) position	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 4,082			$ 1,633	$ 22,444	$ 11,171
Non-cash charges			1,192	$ 2,497	$ 5,794
Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring charges			4,082			1,633	14,663	11,171
Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring costs							10,781	6,479
Non-cash charges							$ 3,882	4,692
Reduction of headcount | position							65
Impairment charge, operating lease								1,968
Impairment charge, leasehold improvements								671
Inventory write down								304
Impairment charge, manufacturing assets								1,749
Voluntary Employee Retirement Plan | Defense Electronics
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost		$ 4,300							$ 4,300
Restructuring charges							$ 2,180		$ 2,120
Reduction of headcount | position		90
Exit of Older Weather Radar Product Lines
Restructuring Cost and Reserve [Line Items]
Business exit costs					5,601
Minimum | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Annual cash savings	$ 30,000
Reduction in inventory	30,000
Maximum | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Annual cash savings	35,000
Reduction in inventory	35,000
One-time charges | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	65,000
Capital investments | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	65,000
Cash charges | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	46,000
Personnel related costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			700			1,050	3,964	4,842
Non-cash charges			0	0	0
Personnel related costs | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	26,000
Restructuring costs							1,784	4,842
Facilities, exit costs and other
Restructuring Cost and Reserve [Line Items]
Restructuring charges			2,190			$ 583	8,997	1,637
Non-cash charges			$ 0	$ 0	$ 0
Facilities, exit costs and other | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	20,000
Restructuring costs							$ 8,997	$ 1,637
Asset write-downs | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	$ 19,000