Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net loss	$ (110,053)	$ (106,658)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,108	539
Stock-based compensation	9,860	8,543
Amortization of debt discount and issuance costs	658	404
Loss on extinguishment of debt	7,155	0
Changes in operating assets and liabilities:
Accounts receivable	(11,333)	(2,310)
Grants and other receivables	68	(196)
Prepaid expenses and other assets	(26)	(762)
Inventory	3,759	(4,698)
Accounts payable	(3,856)	3,171
Accrued expenses and other liabilities	11,845	10,150
Cash used in operating activities	(90,815)	(91,817)
Investing activities:
Purchases of property and equipment	(557)	(1,690)
Cash used in investing activities	(557)	(1,690)
Financing activities:
Proceeds from the sale of common stock	41,438	63,969
Proceeds from long-term debt	77,596	0
Proceeds from the issuance of warrants	2,404	0
Proceeds from the issuance of common stock under employee stock purchase plan	1,008	739
Proceeds from the exercise of stock options	1,038	1,488
Cash paid for financing costs	(5,776)	(6,547)
Payment of withholdings on shares withheld for income taxes	0	(70)
Repayment of Athyrium debt facility	(80,179)	0
Cash provided by financing activities	37,529	59,579
Effects of exchange rate changes on cash and cash equivalents	(3)	64
Net decrease in cash, cash equivalents and restricted cash	(53,846)	(33,864)
Cash, cash equivalents and restricted cash at beginning of period	201,011	234,875
Cash, cash equivalents and restricted cash at end of period	147,165	201,011
Supplemental disclosure of noncash activities:
Cash paid for interest	8,785	8,253
Supplemental disclosure of noncash activities:
Fixed asset purchases within accounts payable and accrued expenses	38	146
Fixed asset additions acquired through tenant allowance	0	361
Financing costs within accounts payable and accrued expenses	483	0
Recognition of initial right-of-use assets	2,483	0
Recognition of initial lease liabilities	$ 2,959	$ 0