ACQUISITIONS (Narrative) (Details) $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended
	May 08, 2017 USD ($)	May 25, 2017 USD ($)	Nov. 07, 2016 USD ($) ft²	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired, Total						$ 162,268	$ 41,308
Goodwill				$ 365,965		365,965		$ 323,616
Revenue, Net				$ 171,189	$ 140,191	$ 478,735	$ 411,954
Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			20 years
Mayday Manufacturing Co [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired, Total			$ 75,000
Goodwill			30,100
Revenue, Net			40,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total			16,600
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities			$ 15,700
Area of Land | ft²			130,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables			$ 7,400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory			11,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Capital Lease Obligation			9,500
Mayday Manufacturing Co [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total			4,800
Mayday Manufacturing Co [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill, Total			$ 32,800
Morgan Schaffer Inc [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 48,800
Goodwill		4,800
Revenue, Net		25,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		3,400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total		1,700
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		2,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory		5,200
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		3,800
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets		$ 34,600
Morgan Schaffer Inc [Member] | Customer Relationships and Developed Technology [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
NRG Systems Inc [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired, Total	$ 38,600
Goodwill	7,500
Revenue, Net	45,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total	9,400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	4,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	5,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Capital Lease Obligation	9,700
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	1,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	4,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	8,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	1,500
NRG Systems Inc [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 17,200
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	14 years