CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (13,174,000)	$ (19,238,000)
Adjustments to reconcile net loss to cash flows used in operating activities:
Amortization of intangible assets	615,000	615,000
Depreciation of property and equipment	33,000	44,000
Amortization of debt discount	171,000	140,000
Non-cash interest expense	323,000	112,000
Loss on extinguishment of debt	0	3,810,000
Stock-based compensation	1,160,000	1,238,000
Changes in operating assets and liabilities:
Accounts receivable and other current assets	(2,320,000)	(2,046,000)
Inventory	(1,221,000)	(607,000)
Accounts payable and accrued expenses	(1,944,000)	2,593,000
Right-of-use assets and operating lease liabilities	(3,000)	35,000
Deferred revenue	15,000	(30,000)
Net cash used in operating activities	(16,345,000)	(13,334,000)
Cash flows from investing activities:
Purchases of property and equipment	(16,000)	(182,000)
Net cash used in investing activities	(16,000)	(182,000)
Cash flows from financing activities:
Proceeds from issuance of stock, net of issuance costs	20,285,000
Proceeds from issuance of long-term debt		35,000,000
Payment of debt issue costs		(894,000)
Payment of long-term debt principal		(20,000,000)
Payment of extinguishment of debt costs		(2,716,000)
Net settlement of stock units to satisfy statutory tax withholding	(19,000)	(20,000)
Proceeds from exercise of stock options and employee stock purchase plan	187,000	264,000
Principal payments on finance lease obligations	(7,000)
Net cash provided by financing activities	20,446,000	11,634,000
Effect of foreign exchange rate changes on cash and cash equivalents	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	4,085,000	(1,882,000)
Cash, cash equivalents and restricted cash at beginning of period	22,364,000	45,411,000
Cash, cash equivalents and restricted cash at end of period	26,449,000	43,529,000
Supplemental cash flow information:
Cash interest paid	1,290,000	1,111,000
Supplemental disclosure of non-cash investing and financing activities:
Stock issuance costs	295,000
Debt issue costs		222,000
Accrued term loan exit fee		$ 2,100,000
Principal portion of finance lease liabilities	$ 7,000