Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts Receivable
Trade accounts receivable	$ 38,525	$ 39,004
Unbilled accounts receivable	5,603	4,223
Accounts receivable, gross	44,128	43,227
Less allowance for doubtful accounts	(338)	(395)
Accounts receivable, net	$ 43,790	$ 42,832