Stockholders' Equity (Deficit) (Details) $ in Thousands	1 Months Ended	3 Months Ended	18 Months Ended
	Oct. 31, 2015 USD ($)	Mar. 31, 2017 USD ($) Vote shares	Mar. 31, 2017 USD ($) shares
Stockholders' Equity (Deficit)
Number of votes per share that common stockholders are entitled to receive | Vote		1
Net proceeds after deducting commissions and other transactions costs		$ 3,399
At-The-Market Issuance Sales Agreement
Stockholders' Equity (Deficit)
Number of shares sold by the entity | shares		215,539	597,256
Value of shares sold by the entity		$ 3,500	$ 9,600
Net proceeds after deducting commissions and other transactions costs		3,400	9,400
Remaining reserved amount under shelf registration		$ 90,400	$ 90,400
Cowen & Co. LLC | At-The-Market Issuance Sales Agreement
Stockholders' Equity (Deficit)
Maximum aggregate offering price	$ 100,000
Notice period of termination of sales agreement	10 days
Cowen & Co. LLC | Maximum | At-The-Market Issuance Sales Agreement
Stockholders' Equity (Deficit)
Percentage of gross proceeds payable as commission	3.00%