Fair Value of Financial Instruments, Significant Unobservable Inputs Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Dec. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year			$ (23,980)	$ (28,770)
Gain from change in fair value			520	260
Balance at end of period	$ (23,460)	$ (28,510)	(23,460)	(28,510)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Other (income) expense, net	566	8,607	6,189	26,003
Fair Value, Measurements, Recurring [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Alternative Investments, Fair Value Disclosure	24,201	23,967	24,201	23,967	$ 24,436
Other (income) expense, net	$ (10)	$ 446	$ 96	$ 1,461