Selected Balance Sheet Information - Schedule of Accrued expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Selected Balance Sheet Information
Accrued clinical consulting services	$ 741	$ 696
Accrued manufacturing costs	617	204
Accrued vendor payments	506	1,028
Vat payable	123
Total	$ 1,987	$ 1,928

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

No definition available.

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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

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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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

n/a

+ References

No definition available.

+ Details

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

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable for statutory income, sales, use, payroll, excise, real, property and other taxes. 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19,20)
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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