Business Acquisitions- WIL Research Additional Information (Details) - WIL Research - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
	Apr. 04, 2016	Jun. 25, 2016	Jun. 25, 2016	Jun. 27, 2015
Business Acquisition [Line Items]
Purchase price	$ 604,800
Assumed liabilities	400
Total purchase price allocation	577,391
Cash acquired	27,400
Goodwill, expected tax deductible amount	$ 19,000
Integration related costs and transaction costs		$ 8,400	$ 12,400
Revenue		55,200	55,200
Net income attributable to common shareholders		$ 1,000	1,000
Amortization of intangible assets and depreciation of fixed assets			2,700	$ 3,400
Reversal of interest expense on borrowings			$ 2,600	5,500
Transaction costs				$ 8,400