ACQUISITIONS - Supplemental Pro Forma Information (Details) - Dover Downs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
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