SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Operating items, net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Other operating items, net	$ 1,305	$ 436
pre-opening expenses relating to the Monarch Black Hawk Expansion project	800	$ 400
professional service fees relating to our construction litigation	100
Colorado legislation lobbing expenses	$ 400