EMPLOYEE BENEFIT PLANS - Allocation of Plan Assets (Details) - Dover Downs Pension Plan - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 28, 2019
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation	100.00%
Plan assets, actual allocation	100.00%
Fair value of plan assets	$ 19,162	$ 17,454
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19,162
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation	60.00%
Plan assets, actual allocation	60.00%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation	40.00%
Plan assets, actual allocation	35.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation	0.00%
Plan assets, actual allocation	5.00%
Equity-large cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 6,702
Equity-large cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,702
Equity-large cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Equity-large cap | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Equity-mid cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	955
Equity-mid cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	955
Equity-mid cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Equity-mid cap | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Equity-small cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	955
Equity-small cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	955
Equity-small cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Equity-small cap | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Equity-international
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,882
Equity-international | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,882
Equity-international | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Equity-international | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,702
Fixed income | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,702
Fixed income | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Fixed income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Money market
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	966
Money market | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	966
Money market | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Money market | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0