Additional Balance Sheet Information - Composition of other assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 26, 2019
Additional Balance Sheet Information
Split dollar life insurance policies	$ 11,411,000	$ 11,411,000
Intangible assets	7,297,000	10,057,000
Other assets	12,393,000	12,468,000
Other Assets, Noncurrent, Total	31,101,000	33,936,000
Business Acquisition, Tradename Intangible Assets	$ 6,900,000	$ 9,500,000