Note 10 - Fair Value Measurements (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jul. 01, 2016	Jun. 30, 2017	Jul. 01, 2016	Dec. 30, 2016	Mar. 18, 2016
Fair Value Adjustment of Warrants			$ 300,000
Derivative Liability	$ 600,000		600,000
Available-for-sale Securities	30,152,000		30,152,000		$ 55,013,000
Goodwill, Impairment Loss	0	$ 0	0	$ 0
Warrant [Member]
Derivative Liability	$ 600,000		$ 600,000			$ 500,000