Note 6 - Employee Stock Benefit Plans - Post-retirement Benefit Obligation to Funded Status and Liability (Details) - Defined Benefit Retirement Plans [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015
Accumulated benefit obligation at beginning of year	$ 2,649	$ 2,428
Interest cost	109	90
Actuarial (gain) loss	(185)	187
Benefits paid	(83)	(56)
Accumulated benefit obligation at end of year	2,490	2,649
Plan assets at end of year
Funded status	$ (2,490)	$ (2,649)