Acquisition of Confluence - Supplemental pro forma financial information (Details) - Confluence - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Revenue	$ 3,676	$ 1,067	$ 4,794	$ 2,303
Gross profit	995	243	1,146	805
Total operating expenses	32,973	16,133	64,072	29,449
Net loss	$ (31,218)	(15,432)	$ (61,447)	(28,106)
Billed revenues
Business Acquisition [Line Items]
Net loss		$ (370)		$ (670)