Pension Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Pension contributions			$ 0	$ 4,102
Pension [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost	$ 1,445	$ 2,225	2,890	4,450
Expected return on plan assets	(2,618)	(3,100)	(5,237)	(6,200)
Recognized net actuarial losses	1,675	1,800	3,351	3,600
Total net pension expense	$ 502	$ 925	$ 1,004	$ 1,850