Equity Investment - Additional Information (Details) - USD ($) shares in Millions	1 Months Ended		3 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Loss from equity method investments			$ 431,000	$ 226,000
PACT Pharma
Schedule of Equity Method Investments [Line Items]
Loss from equity method investments			$ 400,000	200,000
Equity method investment agreement termination date			May 31, 2018
Gain in interest and other income			$ 1,200,000
Equity method investments impairment			0	$ 0
PACT Pharma | Variable Interest Entity
Schedule of Equity Method Investments [Line Items]
Receivable from PACT Pharma			0		$ 100,000
Payable to PACT Pharma			$ 100,000		$ 0
PACT Pharma | Series A Preferred Stock
Schedule of Equity Method Investments [Line Items]
Purchase of common stock, shares	1.0
Purchase of common stock, value	$ 1,000,000
PACT Pharma | Common Stock
Schedule of Equity Method Investments [Line Items]
Purchase of common stock, shares		3.6