Related Party Transactions - Additional Information (Detail)	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 30, 2018 Agreement	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2018 USD ($) Executive RelatedParty $ / shares shares	Sep. 30, 2017 USD ($) shares	Dec. 31, 2017 shares	Jun. 30, 2017 shares
Related Party Transaction [Line Items]
Percentage of outstanding common stock holding				5.00%
Convertible Bonds
Related Party Transaction [Line Items]
Amounts owed to related party				$ 4,000,000
Number of related parties received convertible bonds | RelatedParty					2
Amount purchased in convertible bonds by holders of outstanding common stock and a director				$ 2,000,000
Bonds converted into shares of common stock | shares								2,727,273
Common Stock
Related Party Transaction [Line Items]
Sale of common stock, shares | shares					7,444,528	6,900,000
Avalon BioMedical
Related Party Transaction [Line Items]
Common stock shares held by related parties | shares		786,061			786,061		678,880
Percentage of common stock issued shares					1.00%		1.00%
Avalon BioMedical | In-licensing Agreement
Related Party Transaction [Line Items]
Number of in-licensing agreements | Agreement	2
Payment of upfront fees					$ 5,500,000
Payment of upfront fees in cash					3,500,000
Payment of upfront fees in equity					$ 2,000,000
Avalon BioMedical | Common Stock | In-licensing Agreement
Related Party Transaction [Line Items]
Sale of common stock, shares | shares					107,181
Common stock share price | $ / shares		$ 18.66			$ 18.66
Pharma Essentia
Related Party Transaction [Line Items]
Licenses revenue		$ 0	$ 0		$ 300,000	$ 500,000
Executive Officer
Related Party Transaction [Line Items]
Number of executives | Executive					1
ZenRx
Related Party Transaction [Line Items]
Licenses revenue		0	0		$ 0	0
ZenRx | Clinical Development Services
Related Party Transaction [Line Items]
Payments to related party for services received		100,000	200,000		300,000	500,000
RSJ Consulting LLC
Related Party Transaction [Line Items]
Consulting services incurred		$ 0			$ 0	$ 100,000
RSJ Consulting LLC | Maximum
Related Party Transaction [Line Items]
Consulting services incurred			$ 100,000