Shelf Registration Statement and At-the-Market Offering (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) $ / shares shares
Equity Distribution Agreement [Abstract]
Issuance of common stock (in shares) | shares	570	570
Proceeds from sales	$ 1,504	$ 1,504
Offering costs	$ 203	$ 203
Weighted average sales price (in dollars per share) | $ / shares	$ 3.00	$ 3.00
Maximum [Member]
Equity Distribution Agreement [Abstract]
Aggregate offering price	$ 50,000	$ 50,000
Compensation percentage		5.00%
Common stock aggregate offering price available for issuance	11,293	$ 11,293
JMP Securities [Member] | Maximum [Member]
Equity Distribution Agreement [Abstract]
Aggregate offering price	$ 13,000	$ 13,000