INCOME TAXES INCOME TAXES - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Common stock outstanding (in shares)	32,113,328	37,989,376
Deemed dividend related to changes in fair value of common stock subject to possible redemption		$ 640	$ (2,344)
Increase (decrease) in net deferred tax liabilities	$ (3,700)	5,900
Tax effect	(852)
Deferred income taxes	8,995	5,880	(5,126)
Income tax benefit		6,500
Tax contingency accruals	0	400
Unrecognized tax benefits	0	400	445		$ 106
Cash tax payments	16,519	22,217	$ 41,029
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	600	0
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		0
Delaware | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	2,600
Colorado | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	3,600	$ 3,800
Dover Downs
Operating Loss Carryforwards [Line Items]
Deferred income tax assets	$ 11,879			$ 6,655