Note 9 - Shareholders' Equity - Reconciliation of Outstanding Stock Options (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 30, 2017 USD ($) $ / shares shares
Outstanding (in shares)	356,184
Outstanding (in dollars per share) | $ / shares	$ 98.65
Granted (in shares)	76,082
Granted (in dollars per share) | $ / shares	$ 154.15
Exercised (in shares)	(27,965)
Exercised (in dollars per share) | $ / shares	$ 84.93
Forfeited (in shares)
Outstanding (in shares)	404,301
Outstanding (in dollars per share) | $ / shares	$ 110.04
Outstanding (Year)	4 years 182 days
Outstanding | $	$ 35,488
Exercisable (in shares)	203,745
Exercisable (in dollars per share) | $ / shares	$ 92.36
Exercisable (Year)	3 years 219 days
Exercisable | $	$ 21,486