FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring basis (Details) - Liabilities - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation plan liabilities	$ 33,229	$ 30,928
Interest rate cash flow hedge	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	25,592	23,476
Interest rate cash flow hedge	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	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
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	7,637	$ 7,452
Interest rate cash flow hedge	$ 0