Note 10 - Stockholders' Equity - Stock Options Outstanding (Details) - $ / shares		12 Months Ended
		Dec. 31, 2017		Jan. 01, 2017	Jan. 03, 2016
Outstanding at January 1, 2017 (in shares)		87,500
Granted (in shares)		0		0	0
Exercised (in shares)		5,000
Forfeited or cancelled (in shares)		0
Outstanding at December 31, 2017 (a) (in shares)		82,500	[1]	87,500
Exercisable at December 31, 2017 (b) (in shares)	[2]	82,500
Outstanding at January 1, 2017 (in dollars per share)		$ 8.75
Granted (in dollars per share)		0
Exercised (in dollars per share)		12.43
Forfeited or cancelled (in dollars per share)		0
Outstanding at December 31, 2017 (a) (in dollars per share)		8.53	[1]	$ 8.75
Exercisable at December 31, 2017 (b) (in dollars per share)	[2]	$ 8.53

[1] At December 31, 2017, the weighted-average remaining contractual life of options outstanding was 2.0 years.

[2] At December 31, 2017, the weighted-average remaining contractual life of options exercisable was 2.0 years.