Commitments - Torreya Agreement (Details)						3 Months Ended		12 Months Ended
	Mar. 20, 2018 USD ($)	Sep. 23, 2017 USD ($) shares	Sep. 22, 2017 USD ($) $ / shares	Sep. 08, 2017 USD ($) installment trading_days	Apr. 25, 2016	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Jul. 31, 2017 USD ($)	Jul. 31, 2016 USD ($)	Mar. 01, 2018	Dec. 31, 2017 USD ($)
2014 Consulting Agreement
Other Commitments [Line Items]
Additional consultant fee payable, percentage of perpetuity in excess of $3 million						3.75%
2016 Consulting Agreement
Other Commitments [Line Items]
Percentage of gross funding up to $20 million					5.00%
Percentage of gross funding over $20 million					3.50%
Sponsor fees								$ 687,500	$ 0
Accrued liabilities, current								$ 928,500
Advisory Services
Other Commitments [Line Items]
Sponsor fees						$ 0	$ 84,000
Other commitment				$ 300,000
Number of installment payments | installment				3
Installment payment period				16 months
Stock issued during period, value, issued for services		$ 100,000	$ 133,000	$ 300,000
Milestone payment				$ 140,600
Milestone payment percentage				3.75%
Milestone payment period				15 days
Milestone payment percentage of total consideration with payment				3.375%						3.375%
Milestone payment percentage of total consideration with payment and additional provision				3.5625%
Milestone period				6 years
Milestone payment percentage of total consideration without payment				3.45525%
Milestone payment percentage of total consideration without payment and with additional provision				3.60263%
Threshold trading days | trading_days				10
Stock issued during period for services (in shares) | shares		3,283
Share price of stock issued (in dollars per share) | $ / shares			$ 40.58
Accrued liabilities						$ 434,000					$ 639,000
Payments for accrued obligations	$ 205,000