Note 13 - Stock-based Compensation (Details Textual) - USD ($)	12 Months Ended
	Jan. 03, 2021	Dec. 29, 2019	Dec. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	10 years
Share-based Payment Arrangement, Amount Capitalized	$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0
Share Price (in dollars per share)	$ 3.79
Proceeds from Stock Options Exercised	$ 0	3,600	195,000
Share-based Payment Arrangement, Expense	1,739,000	$ 3,144,000	$ 1,901,000
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount	$ 38,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	0 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	0	0	0
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value, Ending Balance (in dollars per share)	$ 1.09	$ 4.28	$ 5.18
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	20,409	24,131	31,306
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 2.47	$ 9.76	$ 15.40
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	341,926
Employee Stock Ownership Plan (ESOP), Compensation Expense	$ 39,000	$ 60,000	$ 205,000
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Expense	$ 39,000	$ 117,000	$ 131,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	0	0	0
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Expense	$ 1,700,000	$ 3,000,000.0	$ 1,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value, Ending Balance (in dollars per share)	$ 4.99	$ 12.55	$ 17.22	$ 21.56
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)	816,000	353,000	110,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 3.97	$ 10.77	$ 11.90