v2.4.0.6

Fair Value Measurements - Financial Instruments Measured at Fair Value on a Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																																			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Obligations of U.S. Government sponsored enterprises	Dec. 31, 2012 Obligations of U.S. Government sponsored enterprises	Mar. 31, 2013 Obligations of states and political subdivisions	Dec. 31, 2012 Obligations of states and political subdivisions	Mar. 31, 2013 Residential mortgage-backed securities	Dec. 31, 2012 Residential mortgage-backed securities	Mar. 31, 2013 Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Quoted Prices in Active Markets for Identical Assets (Level 1)	Mar. 31, 2013 Significant Other Observable Inputs (Level 2)	Dec. 31, 2012 Significant Other Observable Inputs (Level 2)	Mar. 31, 2013 Significant Unobservable Inputs (Level 3)	Dec. 31, 2012 Significant Unobservable Inputs (Level 3)	Sep. 30, 2012 Significant Unobservable Inputs (Level 3) Auction Rate Securities security	Mar. 31, 2013 Total Fair Value	Dec. 31, 2012 Total Fair Value	Mar. 31, 2013 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1)	Mar. 31, 2013 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1) Obligations of U.S. Government sponsored enterprises	Mar. 31, 2013 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1) Obligations of states and political subdivisions	Mar. 31, 2013 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1) Residential mortgage-backed securities	Mar. 31, 2013 Recurring basis Significant Other Observable Inputs (Level 2)	Mar. 31, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Obligations of U.S. Government sponsored enterprises	Mar. 31, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Obligations of states and political subdivisions	Mar. 31, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Residential mortgage-backed securities	Mar. 31, 2013 Recurring basis Significant Unobservable Inputs (Level 3)	Mar. 31, 2013 Recurring basis Significant Unobservable Inputs (Level 3) Obligations of U.S. Government sponsored enterprises	Mar. 31, 2013 Recurring basis Significant Unobservable Inputs (Level 3) Obligations of states and political subdivisions	Mar. 31, 2013 Recurring basis Significant Unobservable Inputs (Level 3) Residential mortgage-backed securities	Mar. 31, 2013 Recurring basis Total Fair Value	Mar. 31, 2013 Recurring basis Total Fair Value Obligations of U.S. Government sponsored enterprises	Mar. 31, 2013 Recurring basis Total Fair Value Obligations of states and political subdivisions	Mar. 31, 2013 Recurring basis Total Fair Value Residential mortgage-backed securities	Mar. 31, 2013 Portion at Fair Value, Fair Value Disclosure Recurring basis Total Fair Value	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure	Mar. 31, 2013 LIBOR Swap Curve
Assets
Securities available for sale	$ 483,007	$ 640,212	$ 133,547	$ 152,368	$ 51,907	$ 53,003	$ 297,553	$ 434,841										$ 0	$ 0	$ 0	$ 0	$ 479,956	$ 133,547	$ 48,856	$ 297,553	$ 3,051	$ 0	$ 3,051	$ 0	$ 483,007	$ 133,547	$ 51,907	$ 297,553
Portfolio loans																		0				9,794				0				9,794
State tax credits held for sale	20,053	23,020							0	0	0	0	40,850	43,802		40,850	43,802	0				0				20,053				20,053				20,000	35,900
Derivative financial instruments																		0				1,622				0				1,622
Total assets																		0				491,372				23,104				514,476
Liabilities
Derivative financial instruments																		0				1,721				0				1,721
Total liabilities																		0				1,721				0				1,721
Number of securities															3
State tax credits, held for sale	$ 55,923	$ 61,284
Tax credit stream, term	10 years
Years of tax credits generated	10 years
Discount rate, remaining life in years of credits plus																																				20500.00%

X

- Definition

Available-for-sale Securities, Number of Positions

+ References

No definition available.

+ Details

Name:	efsc_AvailableForSaleSecuritiesNumberOfPositions
Namespace Prefix:	efsc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

State Tax Credit Fair Value Input Discount Rate Basis Point Spread

+ References

No definition available.

+ Details

Name:	efsc_StateTaxCreditFairValueInputDiscountRateBasisPointSpread
Namespace Prefix:	efsc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

State tax credits, held for sale

+ References

No definition available.

+ Details

Name:	efsc_StateTaxCreditsHeldForSale
Namespace Prefix:	efsc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

State Tax Credits Held For Sale, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	efsc_StateTaxCreditsHeldForSaleFairValueDisclosure
Namespace Prefix:	efsc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

State Tax Credit Term

+ References

No definition available.

+ Details

Name:	efsc_StateTaxCreditTerm
Namespace Prefix:	efsc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Years of Tax Credits Generated

+ References

No definition available.

+ Details

Name:	efsc_YearsOfTaxCreditsGenerated
Namespace Prefix:	efsc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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

X

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558



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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

+ Details

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

X

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958



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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FIN39-1

-Paragraph 10A, 10B

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 4, 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958



Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611

+ Details

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

X

- Definition

Derivative instrument obligations meeting the definition of a liability which the Company is a party to as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 15

-Paragraph 83

-URI http://asc.fasb.org/extlink&oid=6913464&loc=d3e34841-113949



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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 10

-Subparagraph i

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 6

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

X

- Details

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

X

- Details

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

X

- Definition

This element represents the aggregate of the liabilities reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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

X

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents loan receivable as presented on the statement of financial position which may include mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts, or any other loans which are due the Company as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Glossary Loan

-URI http://asc.fasb.org/extlink&oid=6517073



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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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