Derivative And Financial Instruments (Embedded Derivative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Derivative And Financial Instruments
Beginning Balance	$ (6,402)	$ (4,270)
Initial fair value of earnout derivative		221
Loss on earnout derivative	(270)	(2,353)
Ending Balance	(6,672)	(6,402)
Loss on earnout derivative	$ 270	$ 2,353

Fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as a liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

Name:	us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant