Revision of Prior Period Financial Statements - Schedule of Revised Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 59,104	$ 54,673	$ 52,441	$ 48,334	$ 41,782	$ 38,441	$ 35,292	$ 31,762	$ 214,552	$ 147,277	$ 99,129
Cost of revenue									52,485	38,795	28,203
Gross profit	45,189	40,888	39,429	36,561	30,976	28,488	25,806	23,212	162,067	108,482	70,926
Research and development									37,299	20,860	13,265
Selling, general and administrative									179,523	133,313	85,252
Total operating expenses									216,822	154,173	98,517
Loss from operations									(54,755)	(45,691)	(27,591)
Other income, net									1,895	1,501	1,237
Loss before income taxes									(54,503)	(50,334)	(29,740)
Net loss	$ (17,300)	$ (18,293)	$ (10,725)	$ (8,250)	$ (16,270)	$ (9,727)	$ (13,304)	$ (11,077)	$ (54,568)	$ (50,378)	$ (29,740)
Net loss per common share, basic and diluted	$ (0.65)	$ (0.72)	$ (0.43)	$ (0.34)	$ (0.67)	$ (0.40)	$ (0.56)	$ (0.47)	$ (2.16)	$ (2.11)	$ (1.31)
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue			$ 53,331	$ 47,214	$ 43,155		$ 35,469	$ 30,565		$ 147,293	$ 98,509
Cost of revenue										38,579	27,708
Gross profit			40,506	35,484	32,626		25,979	21,954		108,714	70,801
Research and development										20,750	13,335
Selling, general and administrative										131,582	84,737
Total operating expenses										152,332	98,072
Loss from operations										(43,618)	(27,271)
Other income, net										1,526
Loss before income taxes										(48,236)
Net loss			$ (11,467)	$ (8,019)	$ (14,713)		$ (12,206)	(11,117)		$ (48,280)	$ (29,420)
Net loss per common share, basic and diluted			$ (0.46)	$ (0.33)	$ (0.61)		$ (0.51)			$ (2.02)	$ (1.30)
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue			$ (890)	$ 1,120	$ (1,373)		$ (177)	1,197		$ (16)	$ 620
Cost of revenue										216	495
Gross profit			(1,077)	1,077	(1,650)		(173)	1,258		(232)	125
Research and development										110	(70)
Selling, general and administrative										1,731	515
Total operating expenses										1,841	445
Loss from operations										(2,073)	(320)
Other income, net										(25)
Loss before income taxes										(2,098)
Net loss			$ 742	$ (231)	$ (1,557)		$ (1,098)	$ 40		$ (2,098)	$ (320)
Net loss per common share, basic and diluted			$ 0.03	$ (0.01)	$ (0.06)		$ (0.05)			$ (0.09)	$ (0.01)