Shareholders' Equity (Deficit): Stock Options Activity (Details) - Stock options - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Number of Shares
Outstanding at the beginning of the period (in shares)	668,740	597,700	526,712
Granted (in shares)	69,600	79,400	97,000
Exercised (in shares)	(61,169)	(8,360)	(21,012)
Forfeited (in shares)	(3,501)		(5,000)
Outstanding at the end of the period (in shares)	673,670	668,740	597,700	526,712
Exercisable at the end of the period (in shares)	474,762
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 53.73	$ 48.50	$ 42.87
Granted (in dollars per share)	112.07	91.46	73.31
Exercised (in dollars per share)	26.21	38.46	19.89
Forfeited (in dollars per share)	80.31		56.85
Outstanding at the end of the period (in dollars per share)	62.11	$ 53.73	$ 48.50	$ 42.87
Exercisable at the end of the period (in dollars per share)	$ 49.60
Weighted Average Remaining Contractual Life (years)
Outstanding	6 years 1 month 10 days	6 years 4 months 28 days	6 years 11 months 5 days	7 years 3 months 29 days
Exercisable at the end of the period	5 years 26 days
Intrinsic Value
Outstanding at the beginning of the period	$ 25,582,300	$ 20,973,700	$ 26,446,700
Outstanding at the end of the period	43,139,100	$ 25,582,300	$ 20,973,700	$ 26,446,700
Exercisable at the end of the period	$ 36,345,100
Weighted average assumptions and results used in estimation of fair value of options granted
Risk free interest rate (as a percent)	1.80%	1.71%	1.75%
Expected life (years)	6 years	6 years	6 years
Expected volatility (as a percent)	27.13%	30.15%	33.20%
Dividend yield (as a percent)	1.23%	1.36%	1.66%
Option fair value (in dollars per share)	$ 28.54	$ 24.88	$ 21.02