Stockholders' Equity (Details) - USD ($) $ in Thousands	1 Months Ended			9 Months Ended
	Oct. 31, 2018	Nov. 30, 2017	May 31, 2016	Sep. 30, 2018	Sep. 30, 2017
Common Stock
Aggregate offering price stock sale			$ 60,000
Additional offering price stock sale authorized		$ 75,000
Net proceeds from sale of common stock				$ 25,453	$ 32,642
Subsequent Event
Common Stock
Common stock issued (in shares)	3,884,597
Net proceeds from sale of common stock	$ 1,600
Common Stock
Common Stock
Shares Issued in Connection with Cantor Agreement (in shares)				29,760,486
Aggregate gross offering price available				$ 41,300