PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Mar. 28, 2018	Dec. 27, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 263,819	$ 245,350
Less: accumulated depreciation	63,941	58,255
Property and equipment, net	199,878	187,095
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	173,422	166,963
Landlord funded assets
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,949	7,472
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	33,059	31,608
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	10,298	10,128
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	13,231	12,721
Construction in progress (includes landlord funded assets under construction)
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 22,860	$ 16,458