Summary of Quarterly Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 30, 2017		Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Sep. 24, 2016	Jun. 25, 2016	Mar. 26, 2016	Dec. 31, 2018	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Net sales	$ 883,748		$ 854,261	$ 876,569	$ 852,229	$ 925,097	$ 742,986	$ 730,433	$ 738,204		$ 3,466,807	$ 3,136,720	$ 2,876,748
Gross profit on sales	233,945		222,839	239,879	229,796	258,241	204,864	201,938	207,112		926,459	872,155	786,732
Gain on bargain purchase						23,879					0	23,879	0
Net income	$ 63,654	[1]	$ 4,449	$ 18,475	$ 11,836	$ 41,140	$ 10,628	$ 15,265	$ 20,129		$ 98,414	$ 87,162	$ 59,330
Basic and diluted earnings per share	$ 2.37		$ 0.16	$ 0.69	$ 0.44	$ 1.52	$ 0.40	$ 0.57	$ 0.75		$ 3.66	$ 3.24	$ 2.21
2017 tax reform											$ (49,336)
Federal tax rate											35.00%	35.00%	35.00%
Scenario, Plan [Member]
Federal tax rate										21.00%

[1] The quarter ended December 30, 2017 includes the tax benefit of $49.3 million as a result of revaluing the Company's net deferred tax liability using the enacted Federal tax rate of 21% under the Tax Reform.