EMPLOYEE BENEFIT PLANS - Benefit Obligation, Fair Value of Plan Assets, and Funded Status (Details) - Dover Downs Pension Plan $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Changes in Benefit Obligation
Benefit obligation at acquisition date of March 28, 2019	$ 24,067
Service cost	0
Interest cost	666	$ 666
Actuarial (gain) loss	3,588
Benefits paid	(472)
Benefit obligation at end of year	27,849	27,849
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at acquisition date of March 28, 2019	17,454
Actual return (loss) on plan assets		1,815
Employer contributions		365
Benefits paid		(472)
Settlement payments		0
Fair value of plan assets at end of year	19,162	19,162
Unfunded status at end of year	$ (8,687)	$ (8,687)