Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash Flows From Operating Activities:
Loss from continuing operations	$ (158,436)	$ (171,272)
(Loss) income from discontinued operations, net of income taxes	(192)	10,404
Net loss	(158,628)	(160,868)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	286	261
Stock-based compensation	19,841	17,819
Impairment of second source manufacturer	0	28,197
Loss on disposal of manufacturing equipment	3,057	0
Non-cash lease expense	1,624	1,540
Accretion (amortization) of premium (discount) on debt securities	393	220
Realized gain on mutual funds	(630)	(232)
Realized gain on sale of equity holdings	(5,722)	(1,408)
Unrealized loss on equity holdings	17,266	4,487
Unrealized loss (gain) from transactions denominated in foreign currency	460	495
Bad debt expense (recovery)	(80)	389
Changes in operating assets and liabilities:
Accounts receivable, net	66	0
Other receivables	1,444	7,165
Prepaid expenses and other current assets	1,884	1,159
Other assets	(310)	(317)
Accounts payable and other accrued liabilities	(3,513)	(22,053)
Accrued payroll and benefits	2,596	1,689
Other long-term liabilities	480	(172)
Net cash used in operating activities	(119,486)	(121,629)
Cash Flows From Investing Activities:
Proceeds from maturities of investments	119,814	109,035
Proceeds from sale of equity holdings	5,974	3,954
Purchases of investments	(16,856)	(89,382)
Purchases of property and equipment, net	(221)	(5,535)
Net cash provided by investing activities	108,711	18,072
Cash Flows From Financing Activities:
Proceeds from employees for exercises of stock options	4	13
Proceeds from sale of stock under our employee stock purchase plan	685	650
Net cash provided by financing activities	53,310	85,230
Effect of exchange rates on cash and cash equivalents	(5)	(82)
Net increase (decrease) in cash and cash equivalents	42,530	(18,409)
Cash and cash equivalents — beginning of year	46,009	64,418
Cash and cash equivalents — end of year	88,539	46,009
Supplemental Disclosure of Cash Flow Information:
Cash paid for facility and equipment under operating leases	2,116	2,401
Cash paid for income taxes	12	14
Noncash investing activities:
Additions of property and equipment that remain in accounts payable and other accrued liabilities	0	10,066
Public Offering
Cash Flows From Financing Activities:
Proceeds from issuance of common stock	0	69,665
At-the-market Sales Agreement
Cash Flows From Financing Activities:
Proceeds from issuance of common stock	$ 52,621	$ 14,902