SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment Useful Lives and Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment
Impairment charge	$ 0	$ 0	$ 0
Site improvements | Minimum
Property and Equipment
Estimated useful life	15 years
Site improvements | Maximum
Property and Equipment
Estimated useful life	40 years
Buildings | Minimum
Property and Equipment
Estimated useful life	30 years
Buildings | Maximum
Property and Equipment
Estimated useful life	40 years
Building improvements | Minimum
Property and Equipment
Estimated useful life	5 years
Building improvements | Maximum
Property and Equipment
Estimated useful life	40 years
Furniture and equipment | Minimum
Property and Equipment
Estimated useful life	5 years
Furniture and equipment | Maximum
Property and Equipment
Estimated useful life	10 years
Equipment | Minimum
Property and Equipment
Estimated useful life	3 years
Equipment | Maximum
Property and Equipment
Estimated useful life	20 years