Number of new stock issued during the period.

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Name:	us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Equity, Common Stock (Details) - Common Stock [Member] - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018	Mar. 08, 2018	Aug. 21, 2015	Aug. 20, 2015
Universal Shelf Registration Statement [Member]
Common Stock [Abstract]
Securities offered for sale, aggregate value			$ 100,000
ATM Agreement [Member]
Common Stock [Abstract]
Securities offered for sale, aggregate value		$ 50,000		$ 35,000
Number of shares of common stock sold (in shares)	3,072,610
Average sales price per common share (in dollars per share)	$ 3.91
Aggregate proceeds from sales of common stock	$ 12,000
Sales commissions, fees and other costs associated with issuance of common stock	$ 360