Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CASH FLOWS USED IN OPERATING ACTIVITIES:
Net loss	$ (78,234)	$ (130,437)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,219	1,341
Amortization of discount on marketable securities, net	(132)	(278)
Amortization of debt discount and debt issuance costs	7,628	6,668
Impairment loss on operating lease right of use assets	339
Stock-based compensation	11,863	15,569
(Gain)/Loss on property and equipment disposals	201	0
Changes in operating assets and liabilities:
Inventory	1,053	(1,854)
Accounts receivable, net	(6,891)	(6,516)
Prepaid expenses	5,656	(1,352)
Other current assets	329	724
Operating lease right of use assets	1,010
Other long-term assets	58	166
Accounts payable	1,815	(1,383)
Accrued expenses and other current liabilities	1,556	(4,221)
Lease liability, operating leases	(1,140)
Other non-current liabilities	(48)	(47)
Net cash used in operating activities	(53,718)	(121,620)
CASH FLOWS PROVIDED BY INVESTING ACTIVITIES:
Purchases of property and equipment	0	(71)
Purchases of marketable securities	(33,595)	(499)
Sales and maturities of marketable securities	90,000	45,000
Net cash provided by (used in) investing activities	56,405	44,430
CASH FLOWS PROVIDED BY FINANCING ACTIVITIES:
Proceeds from exercise of stock options and warrant exercises	3,869	8,826
Proceeds from issuance of shares under employee stock purchase plan	1,027	1,741
Net cash provided by financing activities	4,896	10,567
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	7,583	(66,623)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT BEGINNING OF YEAR	59,881	118,619
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT END OF PERIOD	67,464	51,996
SUPPLEMENTAL DISCLOSURES:
Cash paid for interest	4,575	22
Property and equipment purchases in accrued expenses at period end	0	$ 114
Right of use assets obtained in exchange for operating lease liability	$ 8,289