Fair Value Measurements (Assets) (Details) - Fair value, measurements, recurring - USD ($) $ in Thousands	Apr. 01, 2017	Dec. 31, 2016
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	$ 2,728	$ 2,309
Quoted prices in active markets for identical assets (Level 1)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	0	0
Significant other observable inputs (Level 2)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	2,728	2,309
Significant unobservable inputs (Level 3)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments	0	0
Government securities
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	6,071	6,268
Government securities | Quoted prices in active markets for identical assets (Level 1)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	0	0
Government securities | Significant other observable inputs (Level 2)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	6,071	6,268
Government securities | Significant unobservable inputs (Level 3)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	0	0
Corporate bonds
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	6,160	6,017
Corporate bonds | Quoted prices in active markets for identical assets (Level 1)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	0	0
Corporate bonds | Significant other observable inputs (Level 2)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	6,160	6,017
Corporate bonds | Significant unobservable inputs (Level 3)
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, fair value disclosure	$ 0	$ 0