Employee Benefit Plans (Change in Benefit Obligation and Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2017	Dec. 28, 2016	Dec. 30, 2015
Pension Plan [Member]
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 0	$ 67,735
Service cost	0	105	$ 380
Interest cost	0	0	2,983
Actuarial (gains) losses	0	945
Benefits paid	0	(1,057)
Settlements	0	(67,728)
Benefit obligation at end of year	0	0	67,735
Accumulated benefit obligation	0	0
Change in Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0	58,378
Actual return on plan assets	0	861
Employer contributions	0	9,546
Benefits paid	0	(1,057)
Settlements	0	(67,728)
Fair value of plan assets at end of year	0	0	58,378
Funded status	0	0
Other Defined Benefit Plans [Member]
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	2,639	2,669
Service cost	0	0
Interest cost	83	91	107
Actuarial (gains) losses	172	73
Benefits paid	(195)	(194)
Settlements	(91)	0
Benefit obligation at end of year	2,608	2,639	2,669
Accumulated benefit obligation	2,608	2,639
Change in Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	286	194
Benefits paid	(195)	(194)
Settlements	(91)	0
Fair value of plan assets at end of year	0	0	$ 0
Funded status	$ (2,608)	$ (2,639)