Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development expenses	$ 11,100	$ 49,974
General and administrative expenses	16,169	15,601
Gain on sale of assets	(4,910)
Total operating expenses	22,359	65,575
Loss from continuing operations	(22,359)	(65,575)
Other income and expenses:
Interest income	777	1,299
Interest expense	(1,528)	(956)
Other income (expense), net	370	(3,230)
Total other income and expenses	(381)	(2,887)
Net loss from continuing operations before income tax benefit	(22,740)	(68,462)
Income tax benefit	1,473	7,695
Net loss from continuing operations	(21,267)	(60,767)
Discontinued operations:
Income from discontinued operations, net of tax	3,935	20,261
Net loss	(17,332)	(40,506)
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	9	(9)
Other comprehensive loss	9	(9)
Comprehensive loss	$ (17,323)	$ (40,515)
Basic and dilutive net loss per common share
Net loss from continuing operations	$ (1.59)	$ (4.55)
Net income from discontinued operations, net of tax	0.29	1.52
Net loss per share	$ (1.30)	$ (3.03)
Weighted-average common shares used in per share calculations—basic and diluted	13,353	13,343
Cash dividends paid per common share	$ 2.00