Discontinued Operations - Sale of Commercial Business - Schedule of Discontinued Operations and Assets Held for Sale (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Expenses:
Research and development expenses		$ 200
Other income and expenses:
Gain on sale of Commercial Business	$ 5,000	28,000
Income tax expense	(1,100)	(7,600)
Total income from discontinued operations	3,935	20,261
Commercial Business [Member]
Expenses:
Research and development expenses		171
Total expenses		171
Other income and expenses:
Gain on sale of Commercial Business	5,000	28,000
Income from discontinued operations	5,000	27,829
Income tax expense	(1,065)	(7,568)
Total income from discontinued operations	$ 3,935	$ 20,261