Post-Retirement Health Care (Schedule of Cost of Retirement Plans) (Details) - Postretirement Health Coverage - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018
Change in benefit obligation
Benefit obligation at beginning of year	$ 19,552	$ 22,933
Service cost	680	853
Interest cost	795	789
Benefits paid	(1,607)	(1,570)
Actuarial (gain) loss	2,398	(3,453)
Benefit obligation at end of year	21,818	19,552
Change in plan assets
Fair value at beginning of year	0	0
Actual return on assets	0	0
Employer contribution	1,607	1,570
Transferred out	0	0
Benefits paid	(1,607)	(1,570)
Fair value at end of year	0	0
Funded Status of Plan	(21,818)	(19,552)
Amounts recognized in the Statement of Financial Position consist of:
Current liabilities	1,081	1,057
Non-current liabilities	20,737	18,495
Amounts recognized in Accumulated Other Comprehensive Income (Loss) (before tax) consist of:
Actuarial (gain) loss	2,384	(14)
Change in Accumulated Other Comprehensive Income (before tax):
Amount disclosed at beginning of year	(14)	3,565
Actuarial (gain) loss	2,398	(3,453)
Amortization of transition amount	0	(126)
Amount disclosed at end of year	$ 2,384	$ (14)