STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue	$ 12,183,000	$ 18,032,000	$ 33,530,000	$ 34,282,000
Cost of goods sold	1,954,000	3,094,000	5,251,000	5,948,000
Gross profit	10,229,000	14,938,000	28,279,000	28,334,000
Operating expenses:
Research and development	6,062,000	2,846,000	11,500,000	5,449,000
Selling, general and administrative	26,981,000	20,268,000	56,033,000	39,838,000
Total operating expenses	33,043,000	23,114,000	67,533,000	45,287,000
Operating loss	(22,814,000)	(8,176,000)	(39,254,000)	(16,953,000)
Other (income) expense:
Interest income	(248,000)	(1,036,000)	(890,000)	(2,122,000)
Interest expense	526,000	523,000	1,051,000	1,060,000
Other (income) expense, net	(3,000)	(13,000)	(81,000)	25,000
Total other (income) expense	275,000	(526,000)	80,000	(1,037,000)
Loss before income taxes	(23,089,000)	(7,650,000)	(39,334,000)	(15,916,000)
Income taxes	0	0	0	0
Net loss	(23,089,000)	(7,650,000)	(39,334,000)	(15,916,000)
Other comprehensive loss:
Unrealized (loss) gain on investments	(141,000)	35,000	52,000	103,000
Total comprehensive loss	$ (23,230,000)	$ (7,615,000)	$ (39,282,000)	$ (15,813,000)
Net loss per share, basic and diluted (in dollars per share)	$ (0.88)	$ (0.32)	$ (1.56)	$ (0.67)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	26,289,272	23,753,647	25,227,574	23,598,466