Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jun. 27, 2015	Jul. 02, 2016	Jun. 27, 2015
Pension Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 165	$ 228	$ 360	$ 500
Interest cost	1,969	2,027	3,944	4,081
Expected return on plan assets	(2,466)	(2,655)	(4,932)	(5,309)
Amortization of net gain (loss)	746	656	1,520	1,370
Net periodic benefit (income) cost	414	256	892	642
Other Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	60	84	122	180
Interest cost	149	190	305	386
Amortization of prior service (credit) cost	(224)	1	(448)	3
Amortization of net gain (loss)	(20)	(16)	(18)	(13)
Net periodic benefit (income) cost	$ (35)	$ 259	$ (39)	$ 556