Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Cumulative effect of accounting principle adoption of ASU 2016-01		$ 5,481	$ (5,481)
Balance, at Dec. 30, 2017	$ 9,949	1,127,872	5,880	$ (150,857)	$ 992,844
Balance, shares at Dec. 30, 2017	33,047,807			6,149,364
Net income		35,286			35,286
Other comprehensive income (loss), net of reclassification adjustments and tax			(406)		(406)
Dividends paid		(16,139)			(16,139)
Balance, at Jun. 30, 2018	$ 9,949	1,152,499	(8)	$ (150,857)	1,011,583
Balance, shares at Jun. 30, 2018	33,047,807			6,149,364
Balance, at Mar. 31, 2018	$ 9,949	1,141,474	34	$ (150,857)	1,000,600
Balance, shares at Mar. 31, 2018	33,047,807			6,149,364
Net income		19,095			19,095
Other comprehensive income (loss), net of reclassification adjustments and tax			(42)		(42)
Dividends paid		(8,069)			(8,069)
Balance, at Jun. 30, 2018	$ 9,949	1,152,499	(8)	$ (150,857)	1,011,583
Balance, shares at Jun. 30, 2018	33,047,807			6,149,364
Balance, at Dec. 29, 2018	$ 9,949	1,163,545	262	$ (150,857)	1,022,899
Balance, shares at Dec. 29, 2018	33,047,807			6,149,364
Net income		34,780			34,780
Other comprehensive income (loss), net of reclassification adjustments and tax			1,075		1,075
Dividends paid		(16,677)			(16,677)
Balance, at Jun. 29, 2019	$ 9,949	1,181,647	1,337	$ (150,857)	1,042,076
Balance, shares at Jun. 29, 2019	33,047,807			6,149,364
Balance, at Mar. 30, 2019	$ 9,949	1,169,510	883	$ (150,857)	1,029,485
Balance, shares at Mar. 30, 2019	33,047,807			6,149,364
Net income		20,475			20,475
Other comprehensive income (loss), net of reclassification adjustments and tax			454		454
Dividends paid		(8,339)			(8,339)
Balance, at Jun. 29, 2019	$ 9,949	$ 1,181,647	$ 1,337	$ (150,857)	$ 1,042,076
Balance, shares at Jun. 29, 2019	33,047,807			6,149,364