Organization and Description of Business - Schedule of Effect of Correction on Previously Issued Condensed Consolidated Statement of Operations and Comprehensive Loss (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended		39 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Organization And Description Of Business [Line Items]
NET REVENUE	$ 30,368	$ 14,588	$ 48,213	$ 28,904			$ 6,200
COST OF GOODS SOLD	18,608	10,808	29,783	21,658
GROSS PROFIT	11,760	3,780	18,430	7,246
OPERATING EXPENSES:
Sales and distribution	13,709	8,163	22,982	16,956
Research and development	3,342	897	4,505	2,019
General and administrative	10,305	3,130	13,671	5,336
TOTAL OPERATING EXPENSES:	27,356	12,190	41,158	24,311
OPERATING LOSS	(15,596)	(8,410)	(22,728)	(17,065)	$ 29,400	$ 22,600
INTEREST EXPENSE—net	1,281	506	2,494	1,063
OTHER EXPENSE (INCOME)—net	(13)	16	31	(25)
LOSS BEFORE INCOME TAXES	(16,864)	(8,932)	(25,253)	(18,103)
PROVISION FOR INCOME TAXES	15	3	15	3
NET LOSS	$ (16,879)	$ (8,935)	$ (25,268)	$ (18,106)
Net loss per share, basic and diluted	$ (1.38)	$ (0.90)	$ (2.13)	$ (1.95)
Comprehensive loss	$ (16,891)	$ (8,917)	$ (25,255)	$ (18,030)
As Previously Reported
Organization And Description Of Business [Line Items]
NET REVENUE	30,368		48,213
COST OF GOODS SOLD	18,608		29,783
GROSS PROFIT	11,760		18,430
OPERATING EXPENSES:
Sales and distribution	11,828		21,101
Research and development	1,860		3,023
General and administrative	4,414		7,780
TOTAL OPERATING EXPENSES:	18,102		31,904
OPERATING LOSS	(6,342)		(13,474)
INTEREST EXPENSE—net	1,281		2,494
OTHER EXPENSE (INCOME)—net	(13)		31
LOSS BEFORE INCOME TAXES	(7,610)		(15,999)
PROVISION FOR INCOME TAXES	15		15
NET LOSS	$ (7,625)		$ (16,014)
Net loss per share, basic and diluted	$ (0.62)		$ (1.35)
Comprehensive loss	$ (7,637)		$ (16,001)
Correction
OPERATING EXPENSES:
Sales and distribution	1,881		1,881
Research and development	1,482		1,482
General and administrative	5,891		5,891
TOTAL OPERATING EXPENSES:	9,254		9,254
OPERATING LOSS	(9,254)		(9,254)
LOSS BEFORE INCOME TAXES	(9,254)		(9,254)
NET LOSS	$ (9,254)		$ (9,254)
Net loss per share, basic and diluted	$ (0.76)		$ (0.78)
Comprehensive loss	$ (9,254)		$ (9,254)