Pension and Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1,021	$ 969	$ 2,032	$ 1,940
Interest cost	4,619	5,053	9,224	10,111
Expected return on assets	(5,497)	(5,558)	(10,976)	(11,118)
Net amortization and deferrals	2,207	1,251	4,408	2,503
Curtailment/settlement losses	138	0	138	0
Net periodic benefit cost	2,488	1,715	4,826	3,436
Contributions to defined benefit pension plans			430
Expected contributions during the remainder of fiscal year			3,570
Postretirement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	150	138	300	275
Interest cost	285	333	570	665
Expected return on assets	0	0	0	0
Net amortization and deferrals	(114)	(114)	(228)	(227)
Curtailment/settlement losses	0	0	0	0
Net periodic benefit cost	$ 321	$ 357	$ 642	$ 713