Employee Benefit Plans (Details 3) $ in Thousands	Dec. 31, 2017 USD ($)
Amounts in accumulated other comprehensive loss that are expected to be recognized as components of net periodic benefit cost
Prior service cost	$ (455)
Net actuarial loss	252
Pension Benefits
Amounts in accumulated other comprehensive loss that are expected to be recognized as components of net periodic benefit cost
Prior service cost	0
Net actuarial loss	252
Postretirement Benefits
Amounts in accumulated other comprehensive loss that are expected to be recognized as components of net periodic benefit cost
Prior service cost	(455)
Net actuarial loss	$ 0