Capital Stock - Summary of Stock Option Activity (Detail) - USD ($)	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Shares	181,712	188,469	122,547
Granted, Shares	109,352	44,025	81,995
Exercised, Shares	(31,521)	(38,009)	(15,113)
Cancelled, Shares	(8,764)	(12,773)	(960)
Ending Balance, Shares	250,779	181,712	188,469
Options Exercisable, Shares	78,066
Option Price per Share, Cancelled			$ 72.55
Options Exercisable, Option Price per Share	$ 72.06
Beginning Balance, Weighted Average Price	70.78	$ 66.14	57.74
Granted, Weighted Average Price	63.25	81.84	73.84
Exercised, Weighted Average Price	50.77	58.96	39.38
Cancelled, Weighted Average Price	65.24	75.52	72.55
Ending Balance, Weighted Average Price	$ 70.21	70.78	66.14
Ending Balance, Weighted Average Remaining Terms (years)	4 years 10 months 24 days
Options Exercisable, Weighted Average Remaining Terms (years)	2 years 6 months
Ending Balance, Aggregate Intrinsic Value	$ 4,847,742
Options Exercisable, Aggregate Intrinsic Value	$ 1,366,281
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Option Price per Share	$ 41.59	7.74	5.67
Option price per share, Granted	61.68	73.72	68.93
Option Price per Share, Exercised	41.59	7.74	5.67
Option Price per Share, Cancelled	61.68	41.59
Ending Balance, Option Price per Share	41.59	41.59	7.74
Options Exercisable, Option Price per Share	41.59
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Option Price per Share	82.94	82.94	82.59
Option price per share, Granted	83.06	84.93	82.94
Option Price per Share, Exercised	82.94	78.76	78.64
Option Price per Share, Cancelled	74.21	82.94
Ending Balance, Option Price per Share	84.93	$ 82.94	$ 82.94
Options Exercisable, Option Price per Share	$ 84.93