Organization and Operations - At-the-Market Offering (Details) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares	Aug. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) shares
Common stock offering
Additional common stock issued			$ 11,994	$ 61,744
Common Stock
Common stock offering
Percentage of commission payable to underwriter based on proceeds from common stock		0.03
Number of shares issued | shares			3,243,015	5,750,000
Additional common stock issued			$ 3	$ 5
Common Stock | At-the-Market Offering | Cowen
Common stock offering
Aggregate maximum offering amount		$ 10,000
Number of shares issued | shares			368,015
Share price (in dollars per share) | $ / shares	$ 4.35		$ 4.35
Additional common stock issued			$ 1,600
Net proceeds			$ 1,400
Remaining common stock available for sale under offering program	$ 8,400