INCOME TAXES - Provision Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Reconciliation of the tax provision for income taxes (as a percent)
U.S. Federal statutory tax rate (as a percent)	35.00%	35.00%	34.00%
State income taxes, net of federal benefit (as a percent)	2.40%	5.00%	3.00%
Tax-exempt underwriting income of wholly-owned small captive insurance subsidiary (as a percent)	(2.00%)	(2.40%)	(1.30%)
Domestic production deduction (as a percent)	(2.90%)	(2.30%)	(1.00%)
Research and development tax credits (as a percent)	(0.40%)	(0.60%)	(0.60%)
Alternative fuel tax credit (as a percent)	(0.10%)	(0.20%)	(0.20%)
Stock-based compensation (as a percent)		(0.90%)	0.10%
Other, net (as a percent)	0.90%	(1.50%)	0.60%
Effective tax (as a percent)	32.90%	32.10%	34.60%
Reconciliation of the provision for income taxes
U.S. Federal statutory tax rate	$ 6,718,125	$ 4,364,717	$ 5,821,356
State income taxes, net of federal benefit	470,203	617,410	510,783
Tax-exempt underwriting income of wholly-owned small captive insurance subsidiary	(388,168)	(297,243)	(225,480)
Domestic production deduction	(553,476)	(281,688)	(167,800)
Research and development tax credits	(75,000)	(75,000)	(100,000)
Alternative fuel tax credit	(26,000)	(22,750)	(37,370)
Stock-based compensation		(117,395)	16,800
Other, net	173,691	(187,396)	105,070
Effective tax	6,319,375	4,000,655	5,923,359
Reconciliation of the change in the unrecognized tax benefits
Unrecognized tax benefits at the beginning of the period	746,000	659,000	519,611
Gross increases - tax positions in prior periods	229,191	157,657	197,310
Lapse of statute of limitations	(109,191)	(70,657)	(57,921)
Unrecognized tax benefits at the end of the period	$ 866,000	$ 746,000	$ 659,000