Represents the amount pertaining to reserves for uncertain tax positions.

No definition available.

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Namespace Prefix:	snta_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Carryforwards

-URI http://asc.fasb.org/extlink&oid=6506874

+ Details

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

- Details

Name:	us-gaap_TaxCreditCarryforwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Income Taxes (Details 3) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes
Reserves for uncertain tax positions	$ 0snta_ReservesForUncertainTaxPositions	$ 0snta_ReservesForUncertainTaxPositions	$ 0snta_ReservesForUncertainTaxPositions
Liability for uncertain tax positions	0us-gaap_UnrecognizedTaxBenefits	0us-gaap_UnrecognizedTaxBenefits
Federal \| Research and development credits
Income Taxes
Research and development tax credit carryforwards	16,700,000
State \| Research and development credits
Income Taxes
Research and development tax credit carryforwards	$ 7,100,000