Shareholders' Equity (Deficit): Stock Option Plans and Stock-Based Compensation (Details) - Stock options - USD ($)	3 Months Ended		12 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Dec. 26, 2020
Number of Shares
Outstanding at the beginning of the period (in shares)	393,488
Granted (in shares)	10,000	0
Exercised (in shares)	(2,950)
Outstanding at the end of the period (in shares)	400,538		393,488
Exercisable at the end of the period (in shares)	278,583
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 113.19
Granted (in dollars per share)	182.21
Exercised (in dollars per share)	91.10
Outstanding at the end of the period (in dollars per share)	115.08		$ 113.19
Exercisable at the end of the period (in dollars per share)	$ 94.89
Weighted Average Remaining Contractual Life (years)
Outstanding	5 years 5 months 19 days		5 years 7 months 9 days
Exercisable at the end of the period	4 years 1 month 20 days
Intrinsic Value
Outstanding	$ 28,425,900		$ 27,864,900
Exercisable at the end of the period	$ 25,395,100
Weighted average assumptions and results used in estimation of fair value of options granted
Risk free interest rate (as a percent)	0.64%
Expected life (years)	6 years
Expected volatility (as a percent)	25.05%
Dividend yield (as a percent)	2.77%
Option fair value (in dollars per share)	$ 30.02
Additional disclosures
Compensation expense	$ 385,200	$ 140,300
Total unrecognized compensation expense	$ 2,800,000
Weighted average period for recognition of unrecognized compensation expense	2 years 6 months