Accumulated Other Comprehensive Income (Loss) and Shareholders' Equity (Components) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 500,603
Other comprehensive income (loss) before reclassifications	598	$ (686)
Tax (expense) or benefit	(92)	311
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax	121	59
Ending balance	501,110
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5,000)	(5,186)
Ending balance	(4,373)	(5,502)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(1,188)	322
Other comprehensive income (loss) before reclassifications	345	157
Tax (expense) or benefit	0	0
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax	0	0
Ending balance	(843)	479
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(105)	(2)
Other comprehensive income (loss) before reclassifications	27	77
Tax (expense) or benefit	(9)	(27)
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax	0	0
Ending balance	(87)	48
Pension Postretirement Liability
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5,167)	(5,506)
Other comprehensive income (loss) before reclassifications	0	0
Tax (expense) or benefit	0	0
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax	0	0
Ending balance	(5,167)	(5,506)
Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	1,460	0
Other comprehensive income (loss) before reclassifications	226	(920)
Tax (expense) or benefit	(83)	338
Amounts reclassified from accumulated other comprehensive (income) loss, net of tax	121	59
Ending balance	$ 1,724	$ (523)