Consolidated Statement of Stockholders' Equity - USD ($)	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at Dec. 28, 2014	$ 106,535,000	$ 348,000	$ 0	$ 137,647,000	$ (30,962,000)	$ (357,000)	$ (141,000)
Common stock, shares outstanding at Dec. 28, 2014		34,827,240
Stock-based compensation	1,438,000	$ 0	0	1,438,000	0	0	0
Vesting of non-vested shares and excess tax benefits	0	$ 2,000	0	(2,000)	0	0	0
Vesting of non-vested shares, shares		212,650
Net income (loss)	4,000	$ 0	0	0	4,000	0	0
Change in postretirement benefit obligations	22,000	0	0	0	0	22,000	0
Balance at Jan. 03, 2016	107,999,000	$ 350,000	0	139,083,000	(30,958,000)	(335,000)	(141,000)
Common stock, shares outstanding at Jan. 03, 2016		35,039,890
Stock-based compensation	2,053,000	$ 0	0	2,053,000	0	0	0
Vesting of non-vested shares and excess tax benefits	0	$ 3,000	0	(3,000)	0	0	0
Vesting of non-vested shares, shares		218,689
Net income (loss)	45,472,000	$ 0	0	0	45,472,000	0	0
Change in postretirement benefit obligations	(868,000)	0	0	0	0	(868,000)	0
Balance at Jan. 01, 2017	$ 154,656,000	$ 353,000	0	141,133,000	14,514,000	(1,203,000)	(141,000)
Common stock, shares outstanding at Jan. 01, 2017	35,258,579	35,258,579
Stock-based compensation	$ 3,518,000	$ 0	0	3,518,000	0	0	0
Vesting of non-vested shares and excess tax benefits	0	$ 1,000	0	(1,000)	0	0	0
Vesting of non-vested shares, shares		177,673
Net income (loss)	7,159,000	$ 0	0	0	7,159,000	0	0
Change in postretirement benefit obligations	(7,000)	0	0	0	0	(7,000)	0
Balance at Dec. 31, 2017	$ 169,060,000	$ 354,000	0	144,650,000	25,407,000	(1,210,000)	(141,000)
Common stock, shares outstanding at Dec. 31, 2017	35,436,252	35,436,252
Cumulative-effect adjustment from adoption of ASU 2016-09	$ 3,734,000	$ 0	$ 0	$ 0	$ 3,734,000	$ 0	$ 0