Employee Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2017	Dec. 28, 2016	Dec. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Minimum pension liability adjustment	$ 37	$ (21,819)	$ (2,230)
Components of net periodic benefit cost [Abstract]
Settlement loss recognized	21	24,297
Net periodic benefit cost	200	24,600	1,800
Pension Plan [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	105	380
Interest cost	0	0	2,983
Expected return on plan assets	0	0	(3,508)
Amortization of net loss	0	0	1,733
Settlement loss recognized	0	24,297	0
Net periodic benefit cost	0	24,402	1,588
Other comprehensive (income) loss	0	(23,955)	(3,619)
Other Defined Benefit Plans [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	0
Interest cost	83	91	107
Amortization of net loss	92	85	79
Settlement loss recognized	21	0	0
Net periodic benefit cost	196	176	186
Other comprehensive (income) loss	$ 59	$ (12)	$ (36)