SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total provisions for allowance for credit losses on receivables	$ 3,327
Deferred compensation, mutual funds held by the trust	6,455	$ 4,461
Deferred compensation obligations	9,924	6,143
Fair Value, Inputs, Level 2
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred compensation, mutual funds held by the trust	$ 3,322	$ 2,420
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