Note 4 - Earnings Per Share - Distributed and Undistributed Earnings (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Basic Earnings Per Share:
Distributed Earnings (in dollars per share)	$ 0.07	$ 0.07	$ 0.20	$ 0.19
Undistributed Earnings (in dollars per share)	0.07	0.25	0.54	0.59
Total (in dollars per share)	0.14	0.32	0.74	0.78
Diluted Earnings Per Share:
Distributed Earnings (in dollars per share)	0.07	0.07	0.20	0.19
Undistributed Earnings (in dollars per share)	0.07	0.25	0.54	0.59
Total (in dollars per share)	0.14	0.32	0.74	0.78
Basic earnings per share (in dollars per share)	0.14	0.32	0.74	0.78
Diluted earnings per share (in dollars per share)	$ 0.14	$ 0.32	$ 0.74	$ 0.78