Fair Value of Financial Instruments, Significant Unobservable Inputs Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2016	Jun. 28, 2015	Jun. 26, 2016	Jun. 28, 2015	Dec. 27, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year			$ (28,360)	$ (25,340)
Gain from change in fair value			800	150
Balance at end of period	$ (27,560)	$ (25,190)	(27,560)	(25,190)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other (income) expense, net	3,748	1,642	(1,124)	5,407
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure	23,056	32,766	23,056	32,766	$ 22,539
Other (income) expense, net	$ 399	$ (87)	$ 482	$ (70)