COMMITMENTS AND CONTINGENCIES - Obligations by year (Details) - USD ($) $ in Thousands	Dec. 27, 2015	Dec. 28, 2014
Purchase obligations
2016	$ 19,364
2017	10,035
2018	6,669
2019	5,829
2020	5,031
Thereafter	23,581
Total	70,509
Lease Obligation
2016	11,467
2017	10,146
2018	8,819
2019	7,122
2020	5,219
Thereafter	24,735
Total	67,508
Sublease Income
2016	(3,336)
2017	(2,342)
2018	(1,441)
2019	(1,028)
2020	(611)
Thereafter	(1,748)
Total	(10,506)
Net lease obligations
2016	8,131
2017	7,804
2018	7,378
2019	6,094
2020	4,608
Thereafter	22,987
Total	57,002
Contractual Obligation, Fiscal Year Maturity [Abstract]
2016	31,094
2017	20,264
2018	15,869
2019	13,279
2020	10,684
Thereafter	52,929
Total	144,119
Self-Insurance
Workers' compensation obligations
2016	3,599
2017	2,425
2018	1,822
2019	1,356
2020	1,045
Thereafter	6,361
Total	$ 16,608	$ 18,000