Common Stock and Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended			3 Months Ended	6 Months Ended
	Nov. 30, 2016	Apr. 30, 2017	Mar. 31, 2017	Jan. 31, 2017	Dec. 31, 2016	Jun. 30, 2017
Common Stock and Preferred Stock
Net proceeds from issuance of common stock						$ 27,072
Follow-on Offering | Common Stock
Common Stock and Preferred Stock
Number of shares issued				3,571,429
Common stock, price per share				$ 7.00
Net proceeds from issuance of common stock				$ 23,261
2016 ATM Agreement | Common Stock
Common Stock and Preferred Stock
Maximum aggregate proceeds from offering	$ 40,000
Number of shares issued		93,730	177,068	161,341	102,077
Net proceeds from issuance of common stock		$ 855	$ 1,561	$ 1,395	$ 600