Contract Assets and Liabilities Changes in Net Contract Assets (Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Contract assets
Current	$ 1,180	$ 1,238
Contract asset	1,180	1,238
Contract Liabilities
Current	1,074	953
Non-current	249	293
Contract liabilities	$ 1,323	$ 1,246