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		9 Months Ended		12 Months Ended		39 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Organization And Description Of Business [Line Items]
NET REVENUE	$ 40,603	$ 24,672	$ 88,817	$ 53,576			$ 6,200
COST OF GOODS SOLD	23,076	14,262	52,859	35,919
GROSS PROFIT	17,527	10,410	35,958	17,657
OPERATING EXPENSES:
Sales and distribution	18,111	11,560	41,094	28,516
Research and development	3,226	790	7,731	2,810
General and administrative	10,261	2,767	23,932	8,103
TOTAL OPERATING EXPENSES:	31,598	15,117	72,757	39,429
OPERATING LOSS	(14,071)	(4,707)	(36,799)	(21,772)	$ 29,400	$ 22,600
INTEREST EXPENSE—net	875	439	3,368	1,503
OTHER EXPENSE (INCOME)—net	21	(19)	53	(45)
LOSS BEFORE INCOME TAXES	(14,967)	(5,127)	(40,220)	(23,230)
PROVISION FOR INCOME TAXES	8		23	3
NET LOSS	$ (14,975)	$ (5,127)	$ (40,243)	$ (23,233)
Net loss per share, basic and diluted	$ (0.99)	$ (0.49)	$ (3.10)	$ (2.40)
Comprehensive loss	$ (14,962)	$ (5,146)	$ (40,217)	$ (23,176)
As Previously Reported
Organization And Description Of Business [Line Items]
NET REVENUE	40,603		88,817
COST OF GOODS SOLD	23,076		52,859
GROSS PROFIT	17,527		35,958
OPERATING EXPENSES:
Sales and distribution	17,307		38,409
Research and development	2,634		5,657
General and administrative	7,999		15,779
TOTAL OPERATING EXPENSES:	27,940		59,845
OPERATING LOSS	(10,413)		(23,887)
INTEREST EXPENSE—net	875		3,368
OTHER EXPENSE (INCOME)—net	21		53
LOSS BEFORE INCOME TAXES	(11,309)		(27,308)
PROVISION FOR INCOME TAXES	8		23
NET LOSS	$ (11,317)		$ (27,331)
Net loss per share, basic and diluted	$ (0.75)		$ (2.11)
Comprehensive loss	$ (11,304)		$ (27,305)
Correction
OPERATING EXPENSES:
Sales and distribution	804		2,685
Research and development	592		2,074
General and administrative	2,262		8,153
TOTAL OPERATING EXPENSES:	3,658		12,912
OPERATING LOSS	(3,658)		(12,912)
OTHER EXPENSE (INCOME)—net	0
LOSS BEFORE INCOME TAXES	(3,658)		(12,912)
NET LOSS	$ (3,658)		$ (12,912)
Net loss per share, basic and diluted	$ (0.24)		$ (0.99)
Comprehensive loss	$ (3,658)		$ (12,912)