CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows From Operating Activities:
Net loss	$ (51,675)	$ (65,772)	$ (82,751)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	3,321	4,051	3,460
Depreciation and amortization of property and equipment	1,750	1,363	1,598
Amortization of patents and other intangible assets	1,737	1,660	1,662
Changes in fair value of earnout, derivative and warrant liabilities	(387)	(509)	18
Amortization of senior debt discounts	961	1,316	406
Amortization of short-term investment purchase discounts	(131)	(126)	(156)
Deferred interest on debt		2,111	4,738
Loss on debt extinguishment			942
Gain on sale of equipment		(23)	(922)
Other adjustments	48	(91)	5
Changes in operating assets and liabilities:
Accounts receivable	(14,130)	(7,536)	(2,232)
Inventories	1,365	(6,190)	(3,022)
Deferred contract sales organization fees		720	(123)
Other assets	(444)	(414)	(1,278)
Accounts payable	1,270	3,008	2,377
Accrued expenses	14,874	13,171	4,632
Net cash used in operating activities	(41,441)	(53,261)	(70,646)
Cash Flows From Investing Activities:
Purchases of short-term investments	(17,906)	(48,015)	(66,088)
Sales and maturities of short-term investments	36,491	45,118	50,816
Proceeds from sale-leaseback of equipment		3,222
Capital expenditures	(1,361)	(2,497)	(3,550)
Intangible asset expenditures	(5)	(361)	(500)
Net cash provided by (used in) investing activities	17,219	(2,533)	(19,322)
Cash Flows From Financing Activities:
Proceeds from Deerfield debt note, net of fees			58,419
Payment of senior debt and fee			26,063
Proceeds from sale of equipment			415
Proceeds from the issuance of common stock, net of issuance costs	47,292	64,560	13
Payments made on borrowings	(8,425)	(989)	(9,166)
Payments made to purchase treasury stock		(120)	(61)
Payment of payroll taxes withheld for releases of restricted stock units	(46)
Payments made on behalf of Deerfield	(90)	(40)
Net cash provided by financing activities	38,731	63,411	23,557
Increase (decrease) in cash and cash equivalents	14,509	7,617	(66,411)
Cash and Cash Equivalents:
Beginning	31,969	24,352	90,763
Ending	46,478	31,969	24,352
Supplemental Disclosure of Noncash Transactions:
Exit Fee liability incurred in connection with Second Amendment to Facility	750
Derivative liability incurred in connection with First Amendment to Facility	611	2,107
Capital lease liability from purchase of equipment	105
Issuance of senior secured convertible notes in lieu of interest payment		6,586
Issuance of common stock upon conversion of senior secured convertible notes		6,586
Capital lease liability from sale-leaseback transactions		3,222
Prepaid assets included in accounts payable		654
Beneficial conversion feature incurred on convertible notes		613
Deferred contract sales organization fees			597
Supplemental Cash Flow Information:
Interest paid	$ 8,158	$ 6,769	$ 2,857