Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net income	$ 2	$ 14,418
Adjustments to reconcile net income to net cash provided by operating activities:
Non-cash interest expense	1,482	1,736
Share-based compensation expense	1,262	1,116
Amortization of intangible assets	388	388
Amortization of right-of-use lease assets	43	46
Depreciation expense	25	29
Loss on short-term investments	309
Gain on forgiveness of Paycheck Protection Program loan	(2,325)
Gain on sale of non-controlling equity interest	(699)
(Gain) loss on change in fair value of contingent value rights	(153)	450
Inventory fair value step-up adjustment included in cost of product sales		850
Changes in operating assets and liabilities:
Accounts receivable, net	2,881	1,681
Inventory, net	(832)	(211)
Prepaid expenses and other current assets	238	(2,716)
Accounts payable	511	(1,664)
Accrued expenses	(569)	1,101
Lease liabilities	(42)	(46)
Net cash provided by operating activities	2,521	17,178
Financing activities
Purchases of common stock under Stock Repurchase Plan	(5,179)
Net proceeds from issuance of common stock under ESPP	159	81
Net proceeds from issuance of common stock under 2013 Equity Plan		154
Net cash (used for) provided by financing activities	(5,020)	235
Net (decrease) increase in cash, cash equivalents and restricted cash	(2,499)	17,413
Cash, cash equivalents and restricted cash, beginning of period	46,708	21,261
Cash, cash equivalents and restricted cash, end of period	44,209	38,674
Supplemental disclosure of non-cash investing and financing activities
Sale of non-controlling equity interest	699
Forgiveness of Paycheck Protection Program loan	2,325
Reconciliation of cash, cash equivalents and restricted cash to the condensed consolidated balance sheets
Cash and cash equivalents	44,169	38,634
Restricted cash	40	40
Cash, cash equivalents and restricted cash, end of period	$ 44,209	$ 38,674