CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest
Beginning Balance at Dec. 31, 2016	$ 501,009	$ 44,079	$ 0	$ 461,524	$ (5,000)	$ 406
Comprehensive income:
Net income (loss)	89,898			89,795		103
Other comprehensive income (loss), net of tax	1,389				1,389
Cash dividends	(49,557)			(49,557)
Common shares – treasury:
Shares purchased	(58,887)	(1,463)	(22,958)	(34,466)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	30,725	738	29,987
Ending Balance at Dec. 30, 2017	514,577	43,354	7,029	467,296	(3,611)	509
Comprehensive income:
Net income (loss)	93,326			93,377		(51)
Other comprehensive income (loss), net of tax	12				12
Change in ownership of non-controlling interest	(175)			(43)		(132)
Cash dividends	(51,085)			(51,085)
Common shares – treasury:
Shares purchased	(29,424)	(755)	(24,033)	(4,636)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	36,028	983	35,045
Ending Balance at Dec. 29, 2018	563,259	43,582	18,041	504,909	(3,599)	326
Comprehensive income:
Net income (loss)	110,503			110,505		(2)
Other comprehensive income (loss), net of tax	(3,735)				(3,735)
Reclassification of Stranded Tax Effects (ASU 2018-02)	0			739	(739)
Cash dividends	(52,232)			(52,232)
Common shares – treasury:
Shares purchased	(83,907)	(2,286)	(44,424)	(37,197)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	47,481	1,299	46,182
Ending Balance at Dec. 28, 2019	$ 584,368	$ 42,595	$ 19,799	$ 529,723	$ (8,073)	$ 324