Employee Benefit Plan (Details) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Employee Benefit Plan (Textual)    
Retirement savings plan description The Operating Company has a 401(k)-retirement savings plan. Eligible employees must be at least 18 years of age and have completed six months of service. Participants are eligible to receive a matching contribution from the Operating Company of up to the first 3% of compensation plus 50% of participant contributions between 3% and 5% of compensation. Matching contributions, other than safe harbor contributions, vest 33% per year and are 100% vested after three years of service. Safe harbor matching contributions are 100% vested as of the date of the contribution.  
Contributions plan total $ 62,000 $ 53,000