BUSINESS ACQUISITONS - TAQUA, LLC ACQUISITION (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
	Sep. 26, 2016	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Cash, net of cash acquired				$ 42,951	$ 20,669	$ 10,897
Goodwill			$ 49,393	$ 335,716	49,393	$ 40,310
Taqua, LLC
Business Acquisition [Line Items]
Cash, net of cash acquired	$ 19,919
Current assets	10,000
Primary adjustments, increase to current liabilities		$ 400
Primary adjustments, increase to noncurrent liabilities		$ 100
Reversal of contingent liability			10,000
Net reduction in goodwill			(2,200)
Goodwill	9,581
Business combination, pro forma revenue					1,900
Earnings (loss) attributable to acquisition					$ (4,700)
Taqua, LLC | Developed Technology Rights [Member]
Business Acquisition [Line Items]
Increase (decrease) in intangible assets			(12,100)
Taqua, LLC | Customer relationships
Business Acquisition [Line Items]
Increase (decrease) in intangible assets			$ 5,500
Taqua, LLC | Maximum
Business Acquisition [Line Items]
Current assets	$ 65,000