Other Comprehensive Income (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Apr. 01, 2012
Other Comprehensive Income (Textual) [Abstract]
Actuarial loss reclassified to net pension expense on consolidated statements of earning	$ 2,019
Amortization of loss included in net periodic pension costs, tax	774	606
Research and development expenses [Member]
Other Comprehensive Income (Textual) [Abstract]
Actuarial loss reclassified to net pension expense on consolidated statements of earning	381
Selling, general and administrative expenses [Member]
Other Comprehensive Income (Textual) [Abstract]
Actuarial loss reclassified to net pension expense on consolidated statements of earning	938
Cost of goods sold [Member]
Other Comprehensive Income (Textual) [Abstract]
Actuarial loss reclassified to net pension expense on consolidated statements of earning	$ 700