Fair Value of Financial Instruments, Significant Unobservable Inputs Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2017	Sep. 25, 2016	Oct. 01, 2017	Sep. 25, 2016	Dec. 25, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year			$ (28,770)	$ (28,360)
Gain from change in fair value			260	900
Balance at end of period	$ (28,510)	$ (27,460)	(28,510)	(27,460)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other income, net	8,607	6,584	26,003	5,460
Fair Value, Measurements, Recurring [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure	24,405	23,490	24,405	23,490	$ 23,571
Other income, net	$ 446	$ 440	$ 1,461	$ 922