Employee Benefit Plans (Components Of The Change In Unamortized Actuarial Losses, Net, Included In Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2017	Dec. 28, 2016	Dec. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Net gain		$ 603	$ (3,894)
Settlement loss recognized	$ 21	24,297
Minimum pension liability adjustment	37	(21,819)	(2,230)
Total minimum pension liability adjustments included as a component of accumulated other comprehensive loss, net of tax	(1,000)	(900)
Total minimum pension liability adjustments included as a component of accumulated other comprehensive loss, tax benefit	100	100
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Balance, beginning of year	0	(23,955)
Benefit obligation actuarial loss	0	(945)
Amortization of net loss	0	0	1,733
Net gain	0	603
Settlement loss recognized	0	24,297	0
Balance, end of year	0	0	(23,955)
Other Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Balance, beginning of year	(1,033)	(1,045)
Benefit obligation actuarial loss	(172)	(73)
Amortization of net loss	92	85	79
Settlement loss recognized	21	0	0
Balance, end of year	$ (1,092)	$ (1,033)	$ (1,045)