Loans - Summary of Recorded Investment in Impaired Portfolio Loans by Category (Details) - Non-Covered Loans $ in Thousands	3 Months Ended
Mar. 31, 2021 USD ($) loan	Mar. 31, 2020 loan	Dec. 31, 2020 USD ($)
Financing Receivable, Past Due [Line Items]
Total Recorded Investment	$ 36,659		$ 38,507
Recorded Investment With No Allowance	13,820
Financing Receivable, Modifications, Number of Contracts \| loan		3
Nonaccrual	32,225		34,818
Restructured, accruing	3,320		3,559
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	1,114		130
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Recorded Investment	22,508		21,770
Recorded Investment With No Allowance	$ 8,239		8,316
Financing Receivable, Modifications, Number of Contracts \| loan	1
Nonaccrual	$ 18,372		18,158
Restructured, accruing	3,243		3,482
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	893		130
Commercial - investor owned
Financing Receivable, Past Due [Line Items]
Total Recorded Investment	7,379		9,579
Recorded Investment With No Allowance	455		716
Nonaccrual	7,379		9,579
Restructured, accruing	0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Commercial - owner occupied
Financing Receivable, Past Due [Line Items]
Total Recorded Investment	2,589		2,940
Recorded Investment With No Allowance	2,331		6,024
Nonaccrual	2,589		2,940
Restructured, accruing	0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Construction and land development
Financing Receivable, Past Due [Line Items]
Total Recorded Investment	0
Recorded Investment With No Allowance	0		0
Nonaccrual	0
Restructured, accruing	0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0
Residential real estate
Financing Receivable, Past Due [Line Items]
Total Recorded Investment	3,945		4,189
Recorded Investment With No Allowance	2,795		3,190
Financing Receivable, Modifications, Number of Contracts \| loan		2
Nonaccrual	3,868		4,112
Restructured, accruing	77		77
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Other
Financing Receivable, Past Due [Line Items]
Total Recorded Investment	238		29
Recorded Investment With No Allowance	0		18,246
Nonaccrual	17		29
Restructured, accruing	0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	$ 221		$ 0

Number of financing receivables that have been modified by troubled debt restructurings.

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of financing receivable modified as troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554

+ Details

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

- Definition

Amount of financing receivable 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of financing receivable on nonaccrual status.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_FinancingReceivableRecordedInvestmentPastDueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Details

Name:	efsc_LoansByMajorCategoryAxis=efsc_NoncoveredLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=efsc_CommercialAndIndustrialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=efsc_CommercialRealEstateInvestorOwnedFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=efsc_CommercialRealEstateOwnerOccupiedFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=efsc_ConstructionAndLandDevelopmentFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=efsc_ResidentialRealEstateFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=efsc_ConsumerAndOtherPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: