Revenue Recognition Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Contract Assets and Liabilities [Abstract]
Contract with Customer, Liability, Revenue Recognized	$ 37	$ 106
Contract with Customer, Asset, Net, Current	65	65	$ 65
Contract with Customer, Asset, Net, Noncurrent	1,501	1,501	999
Contract with Customer, Asset, Net	1,566	1,566	1,064
Customer Contract Liability Discounts	(1,799)	(1,799)	(1,656)
Customer Contract Liability Rights of Return	(464)	(464)	(325)
Contract with Customer, Liability, Current	$ (2,263)	$ (2,263)	$ (1,981)