Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (27,270,000)	$ (53,060,000)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation, amortization and accretion	739,000	1,459,000
Amortization of right-of-use assets	618,000
Stock-based compensation expense	3,672,000	4,152,000
Loss on extinguishment of debt		53,000
(Gain) Loss on foreign currency translation	(688,000)	(2,379,000)
Interest on note payable to related party	2,297,000	2,219,000
Write-off of inventory	0	779,000
Other, net		106,000
Changes in operating assets and liabilities:
Accounts receivable, net	(957,000)	(170,000)
Inventory	(366,000)	(1,798,000)
Prepaid expenses and other current assets	(150,000)	440,000
Right-of-use and other assets	(356,000)	79,000
Accounts payable	2,154,000	2,253,000
Accrued expenses and other current liabilities	460,000	818,000
Deferred revenue	(6,795,000)	2,049,000
Recognized loss on purchase commitments	(3,984,000)	(5,800,000)
Operating lease payments	(699,000)
Net cash used in operating activities	(31,325,000)	(48,800,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(1,493,000)
Purchase of short-term investments	(24,909,000)
Net cash used in investing activities	(26,402,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Exercise of stock options	18,000
Proceeds from direct placement of common stock		28,000,000
Issuance cost associated with direct placement		(1,610,000)
Principal payments on facility financing obligation	(2,500,000)
Payment of employment taxes related to vested restricted stock units		(184,000)
Proceeds from executive stock purchase plan		335,000
Net cash (used) provided by financing activities	(673,000)	27,150,000
NET DECREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	(58,400,000)	(21,650,000)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD	71,684,000	48,355,000
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	13,284,000	26,705,000
SUPPLEMENTAL CASH FLOWS DISCLOSURES:
Interest paid in cash, net of amounts capitalized		1,860,000
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Payment of note obligations through common stock issuance		20,405,000
Payment of note payable to related party through common stock issuance		8,160,000
Accrued but unpaid debt issuance costs		156,000
Payment of interest on senior convertible notes through common stock issuance	538,000
Property and equipment in progress in accounts payable	790,000
Common stock issuance to settle employee stock purchase plan liability	317,000
Addition of right-of-use assets upon adoption of new lease guidance	5,192,000
At-the-market Issuance
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock pursuant to at-the-market issuance	1,850,000	634,000
Issuance cost of at-the-market transactions	$ (41,000)	$ (25,000)