BUSINESS ACQUISITIONS - WIL Research, Additional Information (Details) - WIL Research - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
	Apr. 04, 2016	Dec. 31, 2016	Dec. 31, 2016	Dec. 26, 2015
Business Acquisition [Line Items]
Purchase price	$ 604,800
Assumed liabilities	400
Purchase price allocation	577,391
Cash acquired	27,400
Goodwill resulting from transaction	$ 19,000
Transaction and integration costs			$ 15,500	$ 3,200
Revenue		$ 176,100
Operating income (loss)		$ 12,500
Additional amortization of intangible assets and depreciation of fixed assets			400	13,600
Reversal of interest expense on borrowings			$ 2,600	10,500
Acquisition-related transaction costs				$ 11,500