REVENUE - Schedule of Respective Liability Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 27, 2018	Dec. 28, 2017	Dec. 27, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Document Period End Date	Jun. 27, 2018
Gift card liability	$ 1,334	$ 1,472	$ 1,472
Deferred revenue, current	305	265
Deferred revenue, long-term	6,653	3,742
Shack sales
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer, asset, net	2,496	2,184
Licensing receivables
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer, asset, net	$ 2,933	$ 1,522