Fair Value Accounting (Changes In Fair Value Included In Consolidated Statements Of Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value Disclosures [Abstract]
Mortgage loans held for sale	$ (5,566)	$ 1,813	$ 5,185
Fair value	45,384	212,663	161,509
Unpaid principal balance	44,943	206,657	157,316
Fair value less aggregate unpaid principal balance	$ 441	$ 6,006	$ 4,193

Changes in the fair value of mortgage loans held for sale that were included in the consolidated statements of income during the reporting period.

No definition available.

+ Details

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Namespace Prefix:	snv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value option, aggregate unpaid principal balance of mortgage loans held for sale.

+ References

No definition available.

+ Details

Name:	snv_FairValueOptionAggregateUnpaidPrincipalBalanceOfMortgageLoansHeldForSale
Namespace Prefix:	snv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624258-113959

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FairValueDisclosuresAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of long-term debt instruments that have contractual principal amounts and for which the fair value option has been elected.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

+ Details

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