Pension Plan (Details) - Presentation of the non-service components of periodic pension cost to Pension benefit - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
General and administrative expenses	$ 1,353	$ 1,445
Operating loss	139	(1,096)
Pension benefit	(34)	(9)
Loss before income taxes	$ 60	(1,255)
Accounting Standards Update 2017-07 [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
General and administrative expenses		1,445
Operating loss		(1,096)
Pension benefit		(9)
Loss before income taxes		(1,255)
Accounting Standards Update 2017-07 [Member] | Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
General and administrative expenses		1,436
Operating loss		(1,089)
Pension benefit
Loss before income taxes		(1,255)
Accounting Standards Update 2017-07 [Member] | Restatement Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
General and administrative expenses		9
Operating loss		(9)
Pension benefit		(9)
Loss before income taxes