Acquisitions - Additional Information (Detail) - USD ($)				3 Months Ended		6 Months Ended
	May. 01, 2015	Feb. 27, 2015	Jan. 30, 2015	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014	Mar. 30, 2015	Dec. 29, 2014	Dec. 28, 2014	Oct. 24, 2014	Oct. 17, 2014	May. 23, 2014	Mar. 31, 2014	Dec. 30, 2013
Business Acquisition [Line Items]
Goodwill				$ 111,591,000	$ 103,294,000	$ 111,591,000	$ 103,294,000			$ 106,220,000
Cash purchase						51,276,000	12,163,000
Net sales				614,683,000	459,473,000	1,067,936,000	848,055,000
Operating Income				38,316,000	31,264,000	55,218,000	43,380,000
Contingent consideration liability				94,068,000	13,000,000	94,068,000	13,000,000	$ 98,505,000	$ 46,850,000					$ 0	$ 0
Favorable fair value adjustment to contingent consideration liability				(6,078,000)	0	(989,000)	0
Net asset value after deducting retained assets and liabilities												$ 10,300,000
Gain on exchange of franchise territory				8,807,000	$ 0	$ 8,807,000	$ 0
Johnson City And Morristown Territory Acquisition [Member]
Business Acquisition [Line Items]
Effective date of business acquisition						May 23, 2014	May 23, 2014
Goodwill													$ 942,000
Goodwill recognized, expected to be deductible for tax purposes													$ 200,000
Knoxville Tennessee Territory Acquisition [Member]
Business Acquisition [Line Items]
Effective date of business acquisition						Oct. 24, 2014	Oct. 24, 2014
Goodwill											$ 3,138,000
Goodwill recognized, expected to be deductible for tax purposes											$ 2,600,000
Cleveland and Cookeville, Tennessee Territory Acquisitions [Member]
Business Acquisition [Line Items]
Effective date of business acquisition						Jan. 30, 2015
Goodwill			$ 1,134,000
Goodwill recognized, expected to be deductible for tax purposes			100,000
Cash purchase			$ 13,800,000
Louisville, Kentucky and Evansville, Indiana [Member]
Business Acquisition [Line Items]
Effective date of business acquisition						Feb. 27, 2015
Goodwill		$ 3,492,000
Goodwill recognized, expected to be deductible for tax purposes		1,600,000
Cash purchase		$ 19,800,000
Paducah And Pikeville Kentucky Territory Acquisitions [Member]
Business Acquisition [Line Items]
Effective date of business acquisition						May 01, 2015
Goodwill	$ 797,000
Goodwill recognized, expected to be deductible for tax purposes	0
Cash purchase	7,500,000
2015 Acquisitions [Member]
Business Acquisition [Line Items]
Net sales				72,500,000		$ 90,500,000
Operating Income				2,700,000		4,400,000
Asset Purchase Agreements [Member]
Business Acquisition [Line Items]
Contingent consideration liability				94,100,000		94,100,000
Contingent consideration liability range, low				6,000,000		6,000,000
Contingent consideration liability range, high				$ 11,000,000		11,000,000
Favorable fair value adjustment to contingent consideration liability						$ 1,000,000
Lexington Expansion [Member]
Business Acquisition [Line Items]
Effective date of business acquisition						May 01, 2015
Goodwill	2,259,000
Goodwill recognized, expected to be deductible for tax purposes	2,200,000
Jackson Territory [Member]
Business Acquisition [Line Items]
Carrying value of assets exchanged	17,500,000
Gain on exchange of franchise territory	$ 8,800,000