Portfolio Loans - Narrative (Details) $ in Millions	Dec. 31, 2015 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans over 90 days past due and still accruing interest \| loan	0
Unadvanced commitments on impaired loans	$ 0.0
Specific reserves on restructured loans	0.2
Unadvanced Commitment on Impaired Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Estimated losses attributable to unadvanced commitments on impaired loans	$ 0.3

Financing Receivable Modifications Reserve

No definition available.

Name:	efsc_FinancingReceivableModificationsReserve
Namespace Prefix:	efsc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Receivable Recorded Investment 90 Days Past Due And Still Accruing Number of Loans

+ References

No definition available.

+ Details

Name:	efsc_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruingNumberOfLoans
Namespace Prefix:	efsc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans and Leases Receivable, Impaired Loans, Commitment to Lend, Reserve

+ References

No definition available.

+ Details

Name:	efsc_LoansAndLeasesReceivableImpairedLoansCommitmentToLendReserve
Namespace Prefix:	efsc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18794-111554

+ Details

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

- Details

Name:	efsc_NatureOfCommitmentsAxis=efsc_UnadvancedCommitmentOnImpairedLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: