Stock Incentive Plans - Summary of Stock Incentive Plans (Details) - USD ($)		3 Months Ended		12 Months Ended
	May 12, 2015	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Mar. 31, 2020
Stock Based Compensation
Option outstanding		4,508,021		3,902,675	4,508,021
Shares available for grant		160,697		479,829	160,697
Shares Available for Grant
Beginning balance (in shares)		479,829
Ending balance (in shares)		160,697		479,829
Stock Options Outstanding
Beginning balance (in shares)		3,902,675
Ending balance (in shares)		4,508,021		3,902,675
RSUs Outstanding
Beginning balance (in shares)		5,613
Ending balance (in shares)		5,613		5,613
Options vested, exercisable and expected to vest
Weighted average grant date fair value of stock options granted (in dollars per share)		$ 0.41	$ 17.50
Number of options vested (in shares)		333,926	7,480
Weighted average fair value of options vested on grant date		$ 2.38	$ 132.81
Inducement options issued and outstanding
Stock Based Compensation
Option outstanding		74		74	74
Stock Options Outstanding
Beginning balance (in shares)		74
Ending balance (in shares)		74		74
2013 Plan | Stock options
Stock Based Compensation
Option shares outstanding					384
Stock Options Outstanding
Options granted (in shares)		0
2014 Plan
Stock Based Compensation
Option outstanding		4,508,021		3,902,675	4,508,021
Shares available for grant		160,697		479,829	160,697
Shares Available for Grant
Beginning balance (in shares)		479,829
Additional shares authorized (in shares)		286,229
Options granted (in shares)		(810,000)
Options cancelled (in shares)		204,639
Ending balance (in shares)		160,697		479,829
Stock Options Outstanding
Beginning balance (in shares)		3,902,675
Options granted (in shares)		810,000
Options cancelled (in shares)		(204,639)
Options canceled not rolled back into the 2013 Plan (in shares)		(15)
Ending balance (in shares)		4,508,021		3,902,675
RSUs Outstanding
Beginning balance (in shares)		5,613
Ending balance (in shares)		5,613		5,613
Weighted Average Stock Option Exercise Price
Beginning balance (in dollars per share)		$ 5.20
Options granted (in dollars per share)		0.45
Options cancelled (in dollars per share)		3.40
Ending balance (in dollars per share)		$ 4.43		$ 5.20
Weighted Average Remaining Contractual Life (Years)
Weighted Average Remaining Contractual Life (Years)		9 years 4 months 2 days		9 years 6 months 22 days
Options vested, exercisable and expected to vest
Options vested and exercisable (in shares)					1,230,522
Options vested and exercisable (in dollars per share)					$ 11.01
Options vested and exercisable (in years)		8 years 11 months 9 days
Options vested and expected to vest (in shares)					3,968,171
Options vested and expected to vest (in dollars per share)					$ 4.83
Options vested and expected to vest (in years)		9 years 3 months 26 days
Options exercised (in shares)		0
Aggregate Intrinsic Value ,outstanding					$ 27,832
2014 Plan | Stock options
Stock Based Compensation
Increase in share reserve based on outstanding number of shares (as a percent)	2.00%
Common Stock
Options vested, exercisable and expected to vest
Share Price					$ 0.48