INCOME TAXES - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2019	Mar. 28, 2018
Income Tax Disclosure [Abstract]
Expected U.S. federal income taxes at statutory rate	$ 1,188	$ 1,297
Expected U.S. federal income taxes at statutory rate, percentage	21.00%	21.00%
State and local income taxes, net of federal benefit	$ 418	$ 412
State and local income taxes, net of federal benefit, percentage	7.40%	6.70%
Foreign withholding taxes	$ 342	$ 531
Foreign withholding taxes, percentage	6.00%	8.60%
Tax credits	$ (376)	$ (277)
Tax credits, percentage	(6.60%)	(4.50%)
Non-controlling interest	$ (323)	$ (454)
Non-controlling interest, percentage	(5.70%)	(7.30%)
Tax effect of change in basis related to ASC 842 adoption	$ 1,161	$ 0
Tax effect of change in basis related to ASC 842 adoption, percent	20.50%	0.00%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ (365)	$ 0
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent	(6.50%)	0.00%
Other	$ 2	$ (311)
Other, percentage	0.10%	(5.00%)
Income tax expense	$ 2,047	$ 1,198
Income tax expense, percentage	36.20%	19.40%