Note 4 - Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2017

Notes Tables

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

	Three Months Ended				Six Months Ended
	June 30, 2017		July 1, 2016		June 30, 2017		July 1, 2016
Stock options	$	239	$	185	$	410	$	248
Restricted stock and restricted stock units		389		360		695		1,003
Total stock-based compensation expense	$	628	$	545	$	1,105	$	1,251

	Three Months Ended				Six Months Ended
	June 30, 2017		July 1, 2016		June 30, 2017		July 1, 2016
Selling, general and administrative expense	$	542	$	453	$	984	$	619
Research, development and engineering costs, net		86		92		121		163
Other operating expenses		—		—		—		469
Total stock-based compensation expense	$	628	$	545	$	1,105	$	1,251

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended						Six Months Ended
	June 30, 2017			July 1, 2016			June 30, 2017			July 1, 2016
Weighted average fair value	$	3.61		$	4.50		$	3.57		$	4.50
Risk-free interest rate		2.04	%		1.72	%		2.06	%		1.72	%
Expected volatility		55	%		55	%		55	%		55	%
Holding period (in years)		6			10			6			10
Expected dividend yield		—	%		—	%		—	%		—	%

Restricted Stock and RSU's [Member]

Notes Tables

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]

	Time-Vested Activity			Weighted Average Fair Value
Nonvested at December 30, 2016		551,224		$	6.90
Granted		206,033			6.67
Vested		(146,754	)		6.47
Forfeited		(73,353	)		6.47
Nonvested at June 30, 2017		537,150		$	6.86

Employee Stock Option [Member]

Notes Tables

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]

	Number of Time-Vested Stock Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Outstanding at December 30, 2016		873,992		$	6.49
Granted		332,469			6.74
Exercised		(16,007	)		4.91
Forfeited or expired		(28,880	)		7.79
Outstanding at June 30, 2017		1,161,574		$	6.55		6.52	$	7,813,773
Exercisable at June 30, 2017		616,615		$	6.14		4.02	$	4,399,729