SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Provision for expected credit losses	$ 38
Deferred compensation, mutual funds held by the trust	9,447	$ 7,596
Level 1
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred compensation, mutual funds held by the trust	$ 5,955	$ 4,244
Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Payment terms, period	30 days
Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Payment terms, period	60 days