Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Consolidated Statements of Income [Abstract]
Net sales	$ 854,261	$ 742,986	$ 2,583,059	$ 2,211,622
Cost of sales, including warehousing and distribution expenses	631,422	538,122	1,890,545	1,597,709
Gross profit on sales	222,839	204,864	692,514	613,913
Operating, general and administrative expenses	216,645	188,901	638,352	542,624
Income from operations	6,194	15,963	54,162	71,289
Investment income and interest expense	657	666	1,893	1,985
Income before provision for income taxes	6,851	16,629	56,055	73,274
Provision for income taxes	2,402	6,001	21,295	27,253
Net income	$ 4,449	$ 10,628	$ 34,760	$ 46,021
Weighted-average shares outstanding, basic and diluted	26,898,443	26,898,443	26,898,443	26,898,443
Cash dividends per share	$ 0.30	$ 0.30	$ 0.90	$ 0.90
Basic and diluted earnings per share	$ 0.16	$ 0.40	$ 1.29	$ 1.71