Selected Balance Sheet Information (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accrued Expenses [Line Items]
Accrued manufacturing costs	$ 74syn_AccruedManufacturingCosts	$ 247syn_AccruedManufacturingCosts
Accrued vendor payments	225syn_AccruedVendorPayments	176syn_AccruedVendorPayments
Accrued milestone payments	1,000syn_AccruedMilestonePayable	350syn_AccruedMilestonePayable
Accrued clinical consulting services	1,347syn_AccruedClinicalConsultingServices	525syn_AccruedClinicalConsultingServices
Total	$ 2,646us-gaap_AccruedLiabilitiesCurrent	$ 1,298us-gaap_AccruedLiabilitiesCurrent

The carrying value of accrued clinical consulting services payable as on balance sheet date.

No definition available.

Name:	syn_AccruedClinicalConsultingServices
Namespace Prefix:	syn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	syn_AccruedExpensesLineItems
Namespace Prefix:	syn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The manufacturing costs incurred in the production of goods for sale.

+ References

No definition available.

+ Details

Name:	syn_AccruedManufacturingCosts
Namespace Prefix:	syn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value of accrued milestone payments payable as on balance sheet date.

+ References

No definition available.

+ Details

Name:	syn_AccruedMilestonePayable
Namespace Prefix:	syn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations and payables pertaining to vendor payments.

+ References

No definition available.

+ Details

Name:	syn_AccruedVendorPayments
Namespace Prefix:	syn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.20)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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