CONDENSED 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. 30, 2017	$ 514,577	$ 43,354	$ 7,029	$ 467,296	$ (3,611)	$ 509
Comprehensive income:
Net income (loss)	60,964			61,014		(50)
Other comprehensive income (loss), net of tax	(584)				(584)
Change in ownership of non-controlling interest				(41)		41
Cash dividends	(38,201)			(38,201)
Common shares – treasury:
Shares purchased	(14,884)	(369)	(9,879)	(4,636)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	31,202	835	30,367
Ending balance at Sep. 29, 2018	553,074	43,820	27,517	485,432	(4,195)	500
Beginning balance at Jun. 30, 2018	525,294	43,736	26,077	458,458	(3,477)	500
Comprehensive income:
Net income (loss)	39,907			39,907		0
Other comprehensive income (loss), net of tax	(717)				(717)
Cash dividends	(12,933)			(12,933)
Common shares – treasury:
Shares purchased	(6,921)	(163)	(6,758)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	8,445	247	8,198
Ending balance at Sep. 29, 2018	553,074	43,820	27,517	485,432	(4,195)	500
Beginning balance at Dec. 29, 2018	563,259	43,582	18,041	504,909	(3,599)	326
Comprehensive income:
Net income (loss)	62,908			62,910		(2)
Other comprehensive income (loss), net of tax	(2,712)				(2,712)
Reclassification of Stranded Tax Effects (ASU 2018-02)	0			739	(739)
Cash dividends	(39,164)			(39,164)
Common shares – treasury:
Shares purchased	(64,877)	(1,797)	(36,401)	(26,679)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	37,932	1,039	36,893
Ending balance at Sep. 28, 2019	560,345	42,824	18,534	505,714	(7,050)	323
Beginning balance at Jun. 29, 2019	529,509	42,875	17,364	474,519	(5,574)	325
Comprehensive income:
Net income (loss)	46,076			46,078		(2)
Other comprehensive income (loss), net of tax	(1,476)				(1,476)
Cash dividends	(13,088)			(13,088)
Common shares – treasury:
Shares purchased	(7,191)	(221)	(5,175)	(1,795)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	6,515	170	6,345
Ending balance at Sep. 28, 2019	$ 560,345	$ 42,824	$ 18,534	$ 505,714	$ (7,050)	$ 323