Revenue Recognition Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Contract Assets and Liabilities [Abstract]
Contract with Customer, Liability, Revenue Recognized	$ 0	$ (68)
Contract with Customer, Asset, Net, Current	64	64	$ 52
Contract with Customer, Asset, Net, Noncurrent	468	468	465
Contract with Customer, Asset, Net	532	532	517
Customer Contract Liability Discounts	(2,482)	(2,482)	(1,133)
Customer Contract Liability Rights of Return	(328)	(328)	(462)
Contract with Customer, Liability, Current	$ (2,810)	$ (2,810)	$ (1,595)