SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Change in Accounting Estimate (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended	15 Months Ended		18 Months Ended
	Oct. 31, 2015 USD ($)	Mar. 31, 2016 USD ($) $ / shares	Dec. 31, 2013 USD ($)	Mar. 31, 2017 USD ($) item	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)
Change in Accounting Estimate
Net book value				$ 223,512			$ 214,899
Net income		$ 4,575		$ 4,872
SEGMENT INFORMATION
Number of operating segments | item				2
Number of reportable segments | item				1
Monarch Black Hawk Parking Structure
Change in Accounting Estimate
Net book value			$ 4,800
Estimated depreciable life			P37Y
Monarch Black Hawk Parking Structure | Service Life
Change in Accounting Estimate
Net book value						$ 2,900		$ 400
Estimated depreciable life					P15M	P18M
Depreciation expense per month					$ 300
Depreciation expense net of tax per month					$ 200
Depreciation expense	$ 40	133
Net income		$ 87
Basic and diluted earnings per share (in dollars per share) | $ / shares		$ 0.01