Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS USED IN OPERATING ACTIVITIES:
Net loss	$ (37,654)	$ (42,760)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	492	633
Amortization of discount on marketable securities, net	(4)	(65)
Amortization of debt discount and debt issuance costs	4,289	3,750
Impairment loss on operating lease right of use assets	0	339
Stock-based compensation	5,459	6,114
Changes in operating assets and liabilities:
Inventory	(679)	564
Accounts receivable, net	(7,082)	(3,992)
Prepaid expenses	2,887	1,470
Other current assets	(368)	446
Operating lease right of use assets	510	500
Other long-term assets	0	43
Accounts payable	3,162	5,654
Accrued expenses and other current liabilities	(3,619)	(6,571)
Lease liability, operating leases	(578)	(565)
Other non-current liabilities	0	(24)
Net cash used in operating activities	(33,185)	(34,464)
CASH FLOWS PROVIDED BY INVESTING ACTIVITIES:
Purchases of marketable securities	(39,907)	0
Sales and maturities of marketable securities	33,000	45,000
Net cash provided by (used in) investing activities	(6,907)	45,000
CASH FLOWS PROVIDED BY FINANCING ACTIVITIES:
Proceeds from exercise of stock options and warrant exercises	0	622
Proceeds from issuance of term loan, net	9,939	0
Proceeds from issuance of shares under employee stock purchase plan	990	1,027
Net cash provided by financing activities	10,929	1,649
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(29,163)	12,185
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT BEGINNING OF YEAR	70,453	59,881
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT END OF PERIOD	41,290	72,066
SUPPLEMENTAL DISCLOSURES:
Cash paid for interest	4,685	4,575
Receivable due from stock options exercises	0	1,895
Cash paid for amounts included in the measurement of operating lease liabilities	682	685
Right of use assets obtained in exchange for operating lease liability	$ 1,110	$ 8,289