FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring basis (Details) - Other Long Term Liabilities [Member] - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Liabilities
Deferred Compensation	$ 31,400,000	$ 30,928,000
Cash flow hedges designated as qualifying instruments	(305,000)
Fair Value, Inputs, Level 1 [Member]
Liabilities
Deferred Compensation	24,081,000	23,476,000
Cash flow hedges designated as qualifying instruments	0
Fair Value, Inputs, Level 2 [Member]
Liabilities
Deferred Compensation	0	0
Cash flow hedges designated as qualifying instruments	(305,000)
Fair Value, Inputs, Level 3 [Member]
Liabilities
Deferred Compensation	0	0
Cash flow hedges designated as qualifying instruments	0
Measured at Net Asset Value as Practical Expedient [Member]
Liabilities
Deferred Compensation	7,319,000	$ 7,452,000
Cash flow hedges designated as qualifying instruments	$ 0