License and Other Agreements - ALS Biopharma Agreement (Details) - ALS Biopharma Agreement - Collaborative arrangement $ / shares in Units, $ in Thousands	1 Months Ended
	Aug. 31, 2015 USD ($) claim prodrug $ / shares shares
License and other agreements
Number of prodrugs of Glutamate Modulating Agents | prodrug	300
Milestone payment to be paid upon regulatory achievement | $	$ 3,000
Milestone payment to be paid for subsequently developed products | $	$ 1,000
Common stock issued (shares)	50,000
Number of claims | claim	1
Common stock warrants issued, immediately exercisable
License and other agreements
Common stock issued (shares)	275,000
Common stock sold, price per share (in dollars per share) | $ / shares	$ 5.60
Common stock warrants issued, exercisable upon filing drug application
License and other agreements
Common stock issued (shares)	325,000
Common stock sold, price per share (in dollars per share) | $ / shares	$ 5.60