Benefit Plans (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	$ 2,957	$ 2,760	$ 2,549
Expense recorded	387	359	369
Other comprehensive (income) loss recorded	(14)	(39)	108
Ending balance	3,182	2,957	2,760
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	840	856	616
Expense recorded	50	23	132
Other comprehensive (income) loss recorded	(14)	(39)	108
Ending balance	$ 876	$ 840	$ 856