Fair Value of Financial Instruments, Assests and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	6 Months Ended
	Jul. 01, 2018	Dec. 31, 2017	Jul. 02, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	$ 3,054	$ 3,126	$ 4,096
Derivatives, assets	22,551	12,226	25,372
Total assets, fair value hierarchy	25,605	15,352	29,468
Derivatives, liabilities	5,191	23,051	22,244
Option Agreement	23,546	23,980	28,500
Total Liabilities	$ 28,737	47,031	50,744
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	45 days
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	30 days
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	90 days
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	$ 3,054	3,126	4,096
Derivatives, assets	0	0	0
Total assets, fair value hierarchy	3,054	3,126	4,096
Derivatives, liabilities	0	0	0
Option Agreement	0	0	0
Total Liabilities	0	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	0	0	0
Derivatives, assets	22,551	12,226	25,372
Total assets, fair value hierarchy	22,551	12,226	25,372
Derivatives, liabilities	5,191	23,051	22,244
Option Agreement	0	0	0
Total Liabilities	5,191	23,051	22,244
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	0	0	0
Derivatives, assets	0	0	0
Total assets, fair value hierarchy	0	0	0
Derivatives, liabilities	0	0	0
Option Agreement	23,546	23,980	28,500
Total Liabilities	$ 23,546	$ 23,980	$ 28,500