Description of Business and Basis of Presentation - Additional Information (Detail) - USD ($)		1 Months Ended
	Apr. 01, 2019	May 23, 2019	Mar. 31, 2019	Dec. 31, 2018
Retained Earnings (Accumulated Deficit)			$ (295,645,000)	$ (295,012,000)
Cash, Cash Equivalents, and Short-Term Investments			200,000
Current liabilities			$ 1,174,000	$ 1,161,000
Proceeds from Issuance of Debt	$ 540,000
Subsequent Event [Member]
Proceeds from Issuance of Debt		$ 540,000