COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Commitments
Outstanding letters of credit	$ 11.6		$ 11.6		$ 13.8
Amount of outstanding surety bonds	103.3		103.3		$ 88.5
Rent expense	2.4	$ 1.9	7.3	$ 6.1
Guarantee Obligations | Downtown Columbia
Commitments
Loss contingency guaranteed amount limit	$ 1.0		$ 1.0