FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring basis (Details) - Liabilities - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation plan liabilities	$ 33,474	$ 33,229
Interest rate cash flow hedge	2,439	189
Quoted prices in active markets Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation plan liabilities	27,040	25,592
Interest rate cash flow hedge	0	0
Significant other observable inputs Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation plan liabilities	0	0
Interest rate cash flow hedge	2,439	189
Significant unobservable inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation plan liabilities	0	0
Interest rate cash flow hedge	0	0
Measured at Net Asset Value as a Practical Expedient
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation plan liabilities	6,434	7,637
Interest rate cash flow hedge	$ 0	$ 0