ACQUISITIONS - Unaudited Supplemental Pro Forma Consolidated Revenue and Net Income (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Dover Downs
Business Acquisition [Line Items]
Revenue	$ 546,634	$ 534,140
Net income	61,945	62,792
Net income applicable to common stockholders	$ 61,945	$ 63,432
Net income per share, basic (in dollars per share)	$ 1.64	$ 1.59
Net income per share, diluted (in dollars per share)	$ 1.64	$ 1.53
Casino KC, Casino Vicksburg, and Shreveport
Business Acquisition [Line Items]
Revenue	$ 465,685	$ 722,136
Net income	$ (7,450)	$ 92,713
Net income per share, basic (in dollars per share)	$ (0.24)	$ 2.46
Net income per share, diluted (in dollars per share)	$ (0.24)	$ 2.45