Summary of Significant Accounting Policies (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Impact from adoption of ASU 2018-02	$ 59	[1]
Reclassification
Increase to Cost of spare parts and equipment sales	1,800
Decrease to Write-down of equipment	$ (1,800)

[1] Reflects the stranded tax effects from change in tax rate as a result of the early adoption of ASU 2018-02 which has been reclassified to retained earnings.