Employee Benefits (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2015 USD ($) plan	Sep. 27, 2014 USD ($)	Oct. 03, 2015 USD ($) plan	Sep. 27, 2014 USD ($)
Components of net periodic benefit cost:
Service cost	$ 2,500	$ 1,924	$ 7,442	$ 5,784
Interest cost	2,592	2,404	7,729	7,225
Expected return on plan assets	(2,179)	(2,173)	(6,467)	(6,537)
Amortization and other	1,379	524	3,505	1,575
Net periodic benefit cost	$ 4,292	$ 2,679	$ 12,209	$ 8,047
Defined benefit pension plan
Target allocation and pension plan asset allocation
Number of defined benefit plans | plan	2		2
Contributions expected to be made to defined benefit pension plans			$ 0