BUSINESS COMBINATION (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended					9 Months Ended		12 Months Ended
	Oct. 22, 2015	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016
Business Acquisition [Line Items]
Acquisition of business, net of cash acquired							$ 0	$ 126,976
Share-based compensation expense							9,716	11,029
Revenue		$ 127,957		$ 108,152			370,395	307,765
Net income (loss)		19,939		18,702			60,450	39,142
Fair values of assets acquired and liabilities assumed [Abstract]
Goodwill		$ 101,812	$ 100,639				$ 101,812		$ 100,639
Impairment expense			1,000
NexPlanar [Member]
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	100.00%
Acquisition of business, net of cash acquired	$ 126,976
Cash Acquired from Acquisition	15,261
Purchase price	142,167
Purchase price adjustment					$ 70
Share-based compensation expense				(451)		$ 605			$ 154
Fair values of assets acquired and liabilities assumed [Abstract]
Total purchase consideration	142,237
Cash	15,261
Accounts receivable	3,052
Inventories	2,768
Prepaid expenses and other current assets	1,712
Property, plant and equipment	6,901
Intangible assets	55,000
Deferred tax assets	20,509
Other long-term assets	1,458
Accounts payable	(1,057)
Accrued expenses and other current liabilities	(1,472)
Deferred tax liabilities	(20,313)
Total identifiable net assets	83,819
Goodwill	$ 58,418
Impairment expense			$ 1,000
Weighted average useful life	7 years 8 months 12 days
Business acquisition, pro forma information [Abstract]
Revenues				108,152				309,172
Net income				$ 18,412				$ 39,915
Earnings per share - basic (in dollars per share)				$ 0.76				$ 1.65
Earnings per share - diluted (in dollars per share)				$ 0.75				$ 1.62
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 55,000
NexPlanar [Member] | Trade Name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 8,000
Useful life	7 years
NexPlanar [Member] | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 8,000
Useful life	11 years
NexPlanar [Member] | Developed Technology - Product Family A [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 32,000
Useful life	7 years
NexPlanar [Member] | Developed Technology - Product Family B [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 2,000
Useful life	9 years
NexPlanar [Member] | In-process Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 5,000