CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) - 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)	21,057			21,107		(50)
Other comprehensive income (loss), net of tax	134				134
Change in ownership of non-controlling interest				(41)		41
Cash dividends	(25,268)			(25,268)
Common shares – treasury:
Shares purchased	(7,963)	(206)	(3,121)	(4,636)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	22,757	588	22,169
Ending balance at Jun. 30, 2018	525,294	43,736	26,077	458,458	(3,477)	500
Beginning balance at Mar. 31, 2018	514,241	43,530	20,124	452,748	(2,662)	501
Comprehensive income:
Net income (loss)	18,596			18,597		(1)
Other comprehensive income (loss), net of tax	(815)				(815)
Cash dividends	(12,887)			(12,887)
Common shares – treasury:
Shares purchased	(1,999)	(53)	(1,946)	0
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	8,158	259	7,899
Ending balance at Jun. 30, 2018	525,294	43,736	26,077	458,458	(3,477)	500
Beginning balance at Dec. 29, 2018	563,259	43,582	18,041	504,909	(3,599)	326
Comprehensive income:
Reclassification of Stranded Tax Effects (ASU 2018-02)				700
Ending balance at Mar. 30, 2019	545,251	43,339	15,921	489,707	(4,040)	324
Beginning balance at Dec. 29, 2018	563,259	43,582	18,041	504,909	(3,599)	326
Comprehensive income:
Net income (loss)	16,831			16,832		(1)
Other comprehensive income (loss), net of tax	(1,236)				(1,236)
Reclassification of Stranded Tax Effects (ASU 2018-02)	0			739	(739)
Cash dividends	(26,075)			(26,075)
Common shares – treasury:
Shares purchased	(57,684)	(1,577)	(31,222)	(24,885)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	31,415	870	30,545
Ending balance at Jun. 29, 2019	529,509	42,875	17,364	474,519	(5,574)	325
Beginning balance at Mar. 30, 2019	545,251	43,339	15,921	489,707	(4,040)	324
Comprehensive income:
Net income (loss)	15,811			15,810		1
Other comprehensive income (loss), net of tax	(1,534)				(1,534)
Cash dividends	(13,203)			(13,203)
Common shares – treasury:
Shares purchased	(32,998)	(929)	(14,274)	(17,795)
Shares issued under Members' Stock Purchase Plan and stock awards, net of tax	16,182	465	15,717
Ending balance at Jun. 29, 2019	$ 529,509	$ 42,875	$ 17,364	$ 474,519	$ (5,574)	$ 325