Common Stock Reserved for Future Issuance (Details) - shares	Mar. 31, 2019	Mar. 31, 2018
Stockholders' equity
Shares reserved for future issuance (in shares)	7,625,748	5,589,766
Common stock warrants
Stockholders' equity
Shares reserved for future issuance (in shares)	6,201,949	4,202,449
Common stock options outstanding
Stockholders' equity
Shares reserved for future issuance (in shares)	758,304	433,389
Common stock options reserved
Stockholders' equity
Shares reserved for future issuance (in shares)	553,014	877,917
Employee stock purchase plan reserved
Stockholders' equity
Shares reserved for future issuance (in shares)	112,481	76,011