Financial impact on date of restructure.

No definition available.

Name:	sfnc_FinancialImpactOnDateOfRestructure
Namespace Prefix:	sfnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

- Definition

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

+ 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=121611835&loc=SL6953676-111524

+ Details

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

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, before troubled debt restructuring, of financing receivable to be modified.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ContractualInterestRateReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=sfnc_RealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans and Allowance for Credit Losses - Loans Restructured as TDRs, Excluding Loans Acquired, Segregated by Class of Loans (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) loan	Jun. 30, 2019 loan	Jun. 30, 2020 USD ($) loan	Jun. 30, 2019 loan
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans \| loan	1	0	1	0
Balance Prior to TDR	$ 147		$ 147
Balance	147		147
Financial Impact on Date of Restructure	0		0
Change in Maturity Date
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	147		147
Change in Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	$ 0		$ 0
Single family residential \| Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of loans \| loan	1		1
Balance Prior to TDR	$ 147		$ 147
Balance	147		147
Financial Impact on Date of Restructure	0		0
Single family residential \| Real Estate \| Change in Maturity Date
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	147		147
Single family residential \| Real Estate \| Change in Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Balance	$ 0		$ 0