Revenue Contract Liabilities (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Movement in Deferred Revenue [Roll Forward]
Contract with Customer, Liability	$ 7,099
Contract with Customer, Liability	7,988
Equipment revenue [Member]
Movement in Deferred Revenue [Roll Forward]
Deferred Revenue, Additions	2,733
Increase (Decrease) in Deferred Revenue	(1,971)
Software revenue [Member]
Movement in Deferred Revenue [Roll Forward]
Deferred Revenue, Additions	4,845
Increase (Decrease) in Deferred Revenue	$ (4,685)