Employee Benefit Plans - 401(k) Plan and Pension Plan (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
401(k) Plan
401(k) Plan
Threshold age, employees eligible for plan	21 years
Threshold period of service, employees eligible for plan	6 months
Threshold hours of service, employees eligible for plan	1,000
Employer's contributions to the plan	$ 44,000	$ 41,000
401(k) Plan | First 3% of employees' salary deferral contribution
401(k) Plan
Employer's matching contribution percentage	100.00%	100.00%
Percentage of employee's gross pay for which employer contributes matching contribution	3.00%	3.00%
401(k) Plan | Next 2% of annual compensation
401(k) Plan
Employer's matching contribution percentage	50.00%	50.00%
Percentage of employee's gross pay for which employer contributes matching contribution	2.00%	2.00%
Pension Plan
401(k) Plan
Percentage of employee's gross pay for which employer contributes matching contribution	25.00%
Threshold age, employees eligible for plan	21 years
Threshold period of service, employees eligible for plan	1 year
Employer's contributions to the plan	$ 67,000	$ 96,000
Employer’s annual contributions to the plan	5.40%	5.40%
Employer’s contributions, percentage per year after first year in the plan	20.00%
Employer’s contributions, vesting period	6 years