Stock-Based Compensation - Equity Incentive Plans (Details) - shares	1 Months Ended	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Class of Stock
Common stock options outstanding		4,705,092	4,220,417
Options outstanding under earlier plans		333,512
Grant of inducement stock option		393,750
2013 Stock Incentive Plan
Class of Stock
Common stock, shares reserved for future issuance	5,653,057
Common shares available for grant		1,571,751
Maximum number of additional common shares	868,372
Common stock options outstanding		3,977,830
Restricted stock units outstanding		376,210