Consolidated Statements of Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Issuance cost	$ 4,925	$ 0	$ 4,811

Amount of increase in additional paid in capital (APIC) resulting from issuance costs from a share-lending arrangement entered into, in contemplation of a convertible debt offering or other financing.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 25
-Paragraph 20A
-URI http://asc.fasb.org/extlink&oid=79512289&loc=SL6757427-112606

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration