Employee Benefit Plans (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	$ 0
Components of net periodic benefit costs:
Interest cost	105,000	$ 113,000
Expected return on plan assets	(147,000)	(138,000)
Amortization of net loss	28,000	25,000
Net periodic benefit/cost	(14,000)	0
Other Postretirement Benefit Plans, Defined Benefit
Components of net periodic benefit costs:
Interest cost	1,000	1,000
Amortization of net loss	(2,000)	(2,000)
Net periodic benefit/cost	$ (1,000)	$ (1,000)
Other Postretirement Benefit Plans, Defined Benefit | Employees Hired before January 1, 2003
Components of net periodic benefit costs:
Benefit based on highest average salary for number of consecutive years	5 years
Number of years for consecutive years calculation	10 years
Other Postretirement Benefit Plans, Defined Benefit | Employees Hired on or after January 1, 2003
Components of net periodic benefit costs:
Percent of annual salary to calculate benefit	2.00%