Revenue, Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Revenue [Abstract]
Revenue recognized	$ 406
Contract liabilities [Abstract]
Customer pre-payments	82	$ 232
Deferred revenue, current	643	700
Deferred revenue, non-current	183	219
Total contract liabilities	$ 908	$ 1,151