Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS USED IN OPERATING ACTIVITIES:
Net loss	$ (87,823)	$ (108,278)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,616	1,785
Amortization of premium/discount on marketable securities, net	237	(246)
Amortization of debt discount and debt issuance costs	13,313	11,638
Impairment loss on operating lease right of use assets	1,510	339
Stock-based compensation	19,821	16,911
Loss on property and equipment disposals	0	201
Changes in operating assets and liabilities:
Inventory	(2,183)	1,299
Accounts receivable, net	2,114	(4,770)
Prepaid expenses	785	(1,359)
Other current assets	(16,232)	344
Operating lease right of use assets	1,472	1,507
Other long-term assets	30	132
Accounts payable	9,737	382
Accrued expenses and other current liabilities	10,632	6,879
Lease liability, operating leases	(1,629)	(1,704)
Other non-current liabilities	0	(71)
Net cash used in operating activities	(46,600)	(75,011)
CASH FLOWS PROVIDED BY INVESTING ACTIVITIES:
Purchases of marketable securities	(39,916)	(36,589)
Sales and maturities of marketable securities	86,900	135,500
Net cash provided by investing activities	46,984	98,911
CASH FLOWS PROVIDED BY FINANCING ACTIVITIES:
Proceeds from exercise of stock options and warrant exercises	0	3,869
Proceeds from issuance of term loan	10,000	0
Payment of debt issuance costs	(61)	0
Proceeds from issuance of shares under employee stock purchase plan	1,621	1,840
Net cash provided by financing activities	11,560	5,709
NET INCREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	11,944	29,609
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT BEGINNING OF PERIOD	70,453	59,881
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT END OF PERIOD	82,397	89,490
SUPPLEMENTAL DISCLOSURES:
Cash paid for interest	9,658	9,150
Cash paid for amounts included in the measurement of operating lease liabilities	1,932	2,068
Right of use assets obtained in exchange for operating lease liability	$ 1,110	$ 8,289