CONDENSED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common shares	Capital in excess of par	Retained earnings	Treasury shares	Total
Balance at at Dec. 30, 2017	$ 643	$ 1,887	$ 66,987	$ (15,195)	$ 54,322
Balance at (in shares) at Dec. 30, 2017	2,574,264			892,097
Consolidated Statements of Shareholders' Equity
Net income (loss)			(6,193)		(6,193)
Compensation of Board of Directors by issuance of treasury shares		43		$ 271	314
Compensation of Board of Directors by issuance of treasury shares (in shares)				(16,000)
Purchase of treasury shares (in shares)				112
Balance at at Mar. 31, 2018	$ 643	1,930	60,794	$ (14,924)	48,443
Balance (in shares) at Mar. 31, 2018	2,574,264			876,209
Balance at at Dec. 30, 2017	$ 643	1,887	66,987	$ (15,195)	54,322
Balance at (in shares) at Dec. 30, 2017	2,574,264			892,097
Consolidated Statements of Shareholders' Equity
Net income (loss)					(4,080)
Balance at at Jun. 30, 2018	$ 643	1,930	62,907	$ (14,924)	50,556
Balance (in shares) at Jun. 30, 2018	2,574,264			876,209
Balance at at Mar. 31, 2018	$ 643	1,930	60,794	$ (14,924)	48,443
Balance at (in shares) at Mar. 31, 2018	2,574,264			876,209
Consolidated Statements of Shareholders' Equity
Net income (loss)			2,113		2,113
Balance at at Jun. 30, 2018	$ 643	1,930	62,907	$ (14,924)	50,556
Balance (in shares) at Jun. 30, 2018	2,574,264			876,209
Balance at at Dec. 29, 2018	$ 643	1,930	61,131	$ (14,928)	48,776
Balance at (in shares) at Dec. 29, 2018	2,574,264			876,409
Consolidated Statements of Shareholders' Equity
Net income (loss)			13,322		13,322
Compensation of Board of Directors by issuance of treasury shares		83		$ 358	441
Compensation of Board of Directors by issuance of treasury shares (in shares)				(21,000)
Purchase of treasury shares				$ (69)	(69)
Purchase of treasury shares (in shares)				3,368
Balance at at Mar. 30, 2019	$ 643	2,013	74,453	$ (14,639)	62,470
Balance (in shares) at Mar. 30, 2019	2,574,264			858,777
Balance at at Dec. 29, 2018	$ 643	1,930	61,131	$ (14,928)	48,776
Balance at (in shares) at Dec. 29, 2018	2,574,264			876,409
Consolidated Statements of Shareholders' Equity
Net income (loss)					8,486
Balance at at Jun. 29, 2019	$ 643	2,013	69,617	$ (14,668)	57,605
Balance (in shares) at Jun. 29, 2019	2,574,264			860,529
Balance at at Mar. 30, 2019	$ 643	2,013	74,453	$ (14,639)	62,470
Balance at (in shares) at Mar. 30, 2019	2,574,264			858,777
Consolidated Statements of Shareholders' Equity
Net income (loss)			(4,836)		(4,836)
Purchase of treasury shares				$ (29)	(29)
Purchase of treasury shares (in shares)				1,752
Balance at at Jun. 29, 2019	$ 643	$ 2,013	$ 69,617	$ (14,668)	$ 57,605
Balance (in shares) at Jun. 29, 2019	2,574,264			860,529