XML 115 R89.htm IDEA: XBRL DOCUMENT v3.20.4
EMPLOYEE BENEFIT PLANS - Assumptions Used (Details) - Dover Downs Pension Plan
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Benefit obligation assumptions:    
Discount rate 2.55% 3.28%
Net periodic benefit cost assumptions:    
Discount rate 3.28% 4.05%
Expected return on plan assets 7.50% 7.50%
Average future years of service 8 years 10 months 24 days