QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Oct. 01, 2021	Jul. 02, 2021	Apr. 02, 2021	Jan. 01, 2021	Oct. 02, 2020	Jul. 03, 2020	Apr. 03, 2020	Dec. 31, 2021	Jan. 01, 2021	Dec. 27, 2019
QUARTERLY FINANCIAL INFORMATION (UNAUDITED)
Contract revenue	$ 92,218	$ 98,297	$ 84,154	$ 79,086	$ 96,897	$ 104,508	$ 83,549	$ 106,026	$ 353,755	$ 390,980	$ 443,099
Income (loss) from operations	1,127	1,443	(7,072)	(4,189)	(5,718)	1,601	(3,841)	(8,269)	(8,691)	(16,227)	9,363
Income tax (benefit) expense	1,370	(236)	(3,663)	(1,458)	(1,892)	(1,586)	(90)	(1,605)	(3,987)	(5,173)	(185)
Net income (loss)	$ (890)	$ 840	$ (4,601)	$ (3,766)	$ (3,997)	$ 2,640	$ (4,985)	$ (8,154)	$ (8,417)	$ (14,496)	$ 4,841
Earnings (Loss) per share:
Basic	$ (0.07)	$ 0.07	$ (0.37)	$ (0.31)	$ (0.33)	$ 0.22	$ (0.43)	$ (0.71)	$ (0.68)	$ (1.23)	$ 0.43
Diluted	$ (0.07)	$ 0.06	$ (0.37)	$ (0.31)	$ (0.33)	$ 0.21	$ (0.43)	$ (0.71)	$ (0.68)	$ (1.23)	$ 0.41
Weighted-average shares outstanding:
Basic	12,660	12,606	12,421	12,147	12,011	11,992	11,682	11,510	12,458	11,793	11,162
Diluted	12,660	13,141	12,421	12,147	12,011	12,417	11,682	11,510	12,458	11,793	11,766