Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
CURRENT ASSETS:
Cash and cash equivalents	$ 138,064	$ 39,643
Accounts receivable, net	3,939	2,850
Inventory	7,014	5,131
Prepaid expenses and other current assets	2,508	1,112
Total current assets	151,525	48,736
Operating lease right-of-use assets	2,645
Property and equipment, net	2,803	2,619
Other assets	566	2,066
TOTAL ASSETS	157,539	53,421
CURRENT LIABILITIES:
Accounts payable	3,967	1,487
Term notes, current portion	3,333	1,667
Accrued liabilities	6,439	6,217
Lease liability, current portion	877
Total current liabilities	14,616	9,371
Lease liability, noncurrent portion	1,916
Term notes, noncurrent portion	11,821	13,383
Convertible preferred stock warrant liability		313
Other liabilities		136
TOTAL LIABILITIES	28,353	23,203
Commitments and contingencies (Note 6)
Convertible preferred stock		152,806
STOCKHOLDERS’ EQUITY (DEFICIT):
Preferred stock
Common stock	28	2
Additional paid-in capital	268,822	4,275
Accumulated deficit	(139,664)	(126,865)
TOTAL STOCKHOLDERS’ EQUITY (DEFICIT)	129,186	(122,588)
TOTAL LIABILITIES, CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT)	$ 157,539	$ 53,421