Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue	$ 197,780	$ 142,642	$ 307,922	$ 222,536
Cost of revenue	149,434	97,429	256,821	171,626
Gross profit	48,346	45,213	51,101	50,910
Operating expenses
Technology and development	16,063	13,033	31,620	25,796
Marketing	27,050	14,435	60,250	27,770
General and administrative	17,654	15,288	39,102	32,062
Total operating expenses	60,767	42,756	130,972	85,628
Income (loss) from operations	(12,421)	2,457	(79,871)	(34,718)
Interest income	1,913	729	4,229	1,307
Interest expense	(2,153)	0	(4,290)	0
Other income, net	36	21	128	179
Net income (loss)	$ (12,625)	$ 3,207	$ (79,804)	$ (33,232)
Net income (loss) per share - basic (in dollars per share)	$ (0.14)	$ 0.04	$ (0.88)	$ (0.40)
Net income (loss) per share - diluted (in dollars per share)	$ (0.14)	$ 0.04	$ (0.88)	$ (0.40)
Weighted average shares - basic (in shares)	91,216,886	83,164,670	90,915,334	82,590,979
Weighted average shares - diluted (in shares)	91,216,886	90,743,178	90,915,334	82,590,979
Foreign currency translation adjustments	$ 37	$ 0	$ 38	$ 0
Unrealized gain on available-for-sale securities	6	0	6	0
Total comprehensive loss	(12,582)	3,207	(79,760)	(33,232)
Service
Revenue	157,872	133,656	246,641	210,498
Cost of revenue	108,528	88,341	192,923	159,196
Product
Revenue	39,908	8,986	61,281	12,038
Cost of revenue	$ 40,906	$ 9,088	$ 63,898	$ 12,430