Business Acquisitions and Divestiture - WIL Research Additional Information (Details) - WIL Research - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Apr. 04, 2016	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016	Feb. 11, 2017	Feb. 10, 2017
Business Acquisition [Line Items]
Purchase price	$ 604,800
Assumed liabilities	400
Purchase price allocation	577,391
Cash acquired	$ 27,400
Goodwill, expected tax deductible amount						$ 14,800	$ 19,000
Integration related costs and transaction costs		$ 700	$ 8,400	$ 1,200	$ 12,400
Revenue			$ 55,200
Operating income					1,000
Amortization of intangible assets and depreciation of fixed assets					2,700
Reversal of interest expense on borrowings					$ 2,600