Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Income Statement [Abstract]
Revenues	$ 288,280	$ 247,889
Costs and expenses:
Operating	198,393	166,016
Selling	50,112	46,304
General and administrative	21,542	19,044
Depreciation and amortization	14,604	14,212
Gain on sale of assets, net	(305)	(653)
Total costs and expenses	284,346	244,923
Income from operations	3,934	2,966
Other income (expense):
Interest expense	(1,946)	(2,151)
Interest income	101	83
Other, net	(1,899)	(1,655)
Income (loss) before income taxes	190	(757)
Income taxes (benefit)	17	(264)
Net income (loss)	$ 173	$ (493)
Net income (loss) per share:
Basic	$ 0.01	$ (0.02)
Diluted	$ 0.01	$ (0.02)
Weighted-average shares outstanding:
Weighted-average shares outstanding--basic and diluted		23,072,000
Basic	23,187,000	23,072,000
Diluted	24,171,000	24,018,000