Stock-Based Compensation (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Beginning Balance	$ 0syn_WarrantLiabilities
Warrants liability	7,376syn_IssuanceOfWarrants
Change in fair value of warrant liabilities	(620)us-gaap_FairValueAdjustmentOfWarrants	0us-gaap_FairValueAdjustmentOfWarrants	0us-gaap_FairValueAdjustmentOfWarrants
Ending Balance	$ 6,756syn_WarrantLiabilities	$ 0syn_WarrantLiabilities

Amount of expense (income) related to adjustment to fair value of warrant liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section 25

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6939902&loc=d3e20148-110875

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