COMMITMENTS AND CONTINGENCIES. - Leases (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Lease Commitments
Rent expense under all operating leases	$ 189,696	$ 166,830	$ 159,010
2017	111,364
2018	31,934
2019	32,892
2020	33,879
2021	11,403
Aggregated future minimum rental payments under noncancelable operating leases	221,472
Consigned Inventories
Consigned inventories to the Company	$ 32,200,000	33,700,000
Period within which chassis are converted and delivered to customers	90 days
Repurchase Commitments
Maximum potential repurchase liability	$ 200,000	1,800,000
Self Insurance
Portion of general liability for which the entity is self-insured, per occurrence	100,000	$ 100,000
Self insurance for employee health benefits, annual coverage per employee	200,000
Worker's compensation liability for which the entity is self insured, per occurrence	$ 250,000