License and Other Agreements (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended						3 Months Ended
	May 09, 2019	May 31, 2019	Mar. 31, 2019	Mar. 31, 2018	Jan. 31, 2018	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018
License and other agreements
Value of common stock issued								$ 281,100	$ 43,842	$ 52,013
FCCDC Warrants
License and other agreements
Number of securities called by warrants (shares)		100,000
Exercise price of warrants (in dollars per share)		$ 56.46
Catalent Agreement | Collaborative arrangement
License and other agreements
Last patent right expiration period (in years)					10 years
Automatic extension period (in years)					1 year
Catalent Agreement | Collaborative arrangement | Maximum
License and other agreements
Milestone payment to be paid upon regulatory achievement					$ 1,500
BMS Agreement
License and other agreements
Upfront payment under the BMS Amendment				$ 50,000
Biotech Value Advisors Agreement | Collaborative arrangement | Maximum
License and other agreements
Commercial milestone payment to be paid			$ 2,000
FCCDC Agreement | Collaborative arrangement
License and other agreements
Common stock issued (shares)		100,000
Value of common stock issued		$ 5,646
Development milestone payment to be paid		4,500
Development milestone payments to be paid per each additional NDA filing		1,000
Performance milestone payment to be paid		$ 1,500
Time period for payment of performance milestone		30 months
FCCDC Agreement | Collaborative arrangement | Minimum
License and other agreements
Earned royalty payment per agreement (percent)		0.00%
FCCDC Agreement | Collaborative arrangement | Maximum
License and other agreements
Earned royalty payment per agreement (percent)		10.00%
Yale Agreement | Collaborative arrangement
License and other agreements
Milestone payment to be paid upon regulatory achievement	$ 2,000
Common stock issued (shares)							250,000
Right to purchase securities in specified future equity offering (as a percent)							10.00%
Minimum annual royalty payment to be paid upon sale of product	$ 1,000
Notice period to terminate agreement	90 days
Yale Agreement | Collaborative arrangement | Maximum
License and other agreements
Extension of due diligence requirements (in years)	1 year
Amount of payment subject to due diligence extension	$ 150
MGH Agreement | Collaborative arrangement | Minimum
License and other agreements
Royalties to be paid per agreement (percent)						0.00%
MGH Agreement | Collaborative arrangement | Maximum
License and other agreements
Upfront payment under the BMS Amendment						$ 750
Commercial milestone payment to be paid						$ 2,500
Royalties to be paid per agreement (percent)						10.00%