XML 131 R69.htm IDEA: XBRL DOCUMENT v2.4.1.9
Loans (Schedule Of Loans Individually Evaluated For Impairment) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Financing Receivable, Impaired [Line Items]      
Recorded Investment $ 48,399us-gaap_ImpairedFinancingReceivableRecordedInvestment $ 60,745us-gaap_ImpairedFinancingReceivableRecordedInvestment  
Unpaid Principal Balance 48,416us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance 60,782us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance  
Related Allowance 816us-gaap_ImpairedFinancingReceivableRelatedAllowance 4,400us-gaap_ImpairedFinancingReceivableRelatedAllowance  
Average Impaired Balance 46,643us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 56,930us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment 79,400us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Interest Income Recognized while impaired 1,784us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod 1,987us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod 2,400us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Commercial Loan [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 370us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
1,161us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
Without a related allowance, Unpaid Principal Balance 369us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
1,167us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
Without a related allowance, Average Impaired Balance 430us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
1,518us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
Without a related allowance, Interest Income Recognized while impaired 27us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
98us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
With a related allowance, Recorded Investment 125us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
855us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
With a related allowance, Unpaid Principal Balance 125us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
855us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
With a related allowance, Related Allowance 81smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
406smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
With a related allowance, Average Impaired Balance 38us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
1,013us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
With a related allowance, Interest Income Recognized while impaired 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
 
Owner Occupied [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 5,362us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
8,434us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
Without a related allowance, Unpaid Principal Balance 5,361us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
8,434us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
Without a related allowance, Average Impaired Balance 5,309us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
7,675us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
Without a related allowance, Interest Income Recognized while impaired 192us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
226us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
With a related allowance, Recorded Investment 5,446us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
4,116us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
With a related allowance, Unpaid Principal Balance 5,446us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
4,116us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
With a related allowance, Related Allowance 287smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
305smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
With a related allowance, Average Impaired Balance 5,461us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
3,945us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
With a related allowance, Interest Income Recognized while impaired 216us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
184us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_OwnerOccupiedMember
 
Non Owner Occupied [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 3,645us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
5,075us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
Without a related allowance, Unpaid Principal Balance 3,647us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
5,077us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
Without a related allowance, Average Impaired Balance 4,420us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
5,110us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
Without a related allowance, Interest Income Recognized while impaired 199us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
253us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
With a related allowance, Recorded Investment 2,860us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
747us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
With a related allowance, Unpaid Principal Balance 2,860us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
755us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
With a related allowance, Related Allowance 74smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
175smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
With a related allowance, Average Impaired Balance 1,003us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
515us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
With a related allowance, Interest Income Recognized while impaired 40us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
28us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonOwnerOccupiedMember
 
Land And Land Improvements [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 13,410us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
14,732us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
Without a related allowance, Unpaid Principal Balance 13,410us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
14,737us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
Without a related allowance, Average Impaired Balance 14,149us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
11,628us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
Without a related allowance, Interest Income Recognized while impaired 483us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
325us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
With a related allowance, Recorded Investment 898us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
10,532us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
With a related allowance, Unpaid Principal Balance 898us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
10,532us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
With a related allowance, Related Allowance 46smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
3,186smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
With a related allowance, Average Impaired Balance 933us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
11,310us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
With a related allowance, Interest Income Recognized while impaired 42us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
147us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_LandAndLandImprovementsMember
 
Construction [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
Without a related allowance, Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
Without a related allowance, Average Impaired Balance 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
Without a related allowance, Interest Income Recognized while impaired 0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
With a related allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
With a related allowance, Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
With a related allowance, Related Allowance 0smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
With a related allowance, Average Impaired Balance 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
With a related allowance, Interest Income Recognized while impaired 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_ConstructionMember
 
Non Jumbo [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 4,289us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
3,587us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
Without a related allowance, Unpaid Principal Balance 4,300us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
3,595us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
Without a related allowance, Average Impaired Balance 3,853us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
2,858us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
Without a related allowance, Interest Income Recognized while impaired 185us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
157us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
With a related allowance, Recorded Investment 2,627us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
2,485us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
With a related allowance, Unpaid Principal Balance 2,628us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
2,487us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
With a related allowance, Related Allowance 282smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
256smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
With a related allowance, Average Impaired Balance 2,093us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
2,292us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
With a related allowance, Interest Income Recognized while impaired 98us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
107us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_NonJumboMember
 
Jumbo [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 7,589us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
7,862us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
Without a related allowance, Unpaid Principal Balance 7,594us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
7,867us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
Without a related allowance, Average Impaired Balance 7,761us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
7,910us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
Without a related allowance, Interest Income Recognized while impaired 241us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
405us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
With a related allowance, Recorded Investment 885us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
900us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
With a related allowance, Unpaid Principal Balance 886us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
901us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
With a related allowance, Related Allowance 46smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
37smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
With a related allowance, Average Impaired Balance 892us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
906us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
With a related allowance, Interest Income Recognized while impaired 45us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
45us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_JumboMember
 
Home Equity [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 809us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
186us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Without a related allowance, Unpaid Principal Balance 808us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
186us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Without a related allowance, Average Impaired Balance 265us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
186us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Without a related allowance, Interest Income Recognized while impaired 14us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
11us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
With a related allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
27us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
With a related allowance, Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
26us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
With a related allowance, Related Allowance 0smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
22smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
With a related allowance, Average Impaired Balance 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
27us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
With a related allowance, Interest Income Recognized while impaired 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
 
Consumer Portfolio Segment [Member]      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 84us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
26us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Without a related allowance, Unpaid Principal Balance 84us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
27us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Without a related allowance, Average Impaired Balance 36us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
28us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Without a related allowance, Interest Income Recognized while impaired 2us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
1us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
With a related allowance, Recorded Investment 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
20us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
With a related allowance, Unpaid Principal Balance 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
20us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
With a related allowance, Related Allowance 0smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
13smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
With a related allowance, Average Impaired Balance 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
9us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
With a related allowance, Interest Income Recognized while impaired 0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
0us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerPortfolioSegmentMember
 
Total Without a Related Allowance      
Financing Receivable, Impaired [Line Items]      
Without a related allowance, Recorded Investment 35,558us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
41,063us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
 
Without a related allowance, Unpaid Principal Balance 35,573us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
41,090us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
 
Without a related allowance, Average Impaired Balance 36,223us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
36,913us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
 
Without a related allowance, Interest Income Recognized while impaired 1,343us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
1,476us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithoutRelatedAllowanceMember
 
Total With a Related Allowance      
Financing Receivable, Impaired [Line Items]      
With a related allowance, Recorded Investment 12,841us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
19,682us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
 
With a related allowance, Unpaid Principal Balance 12,843us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
19,692us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
 
With a related allowance, Related Allowance 816smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
4,400smmf_ImpairedFinancingReceivableWithRelatedAllowanceRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
 
With a related allowance, Average Impaired Balance 10,420us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
20,017us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
 
With a related allowance, Interest Income Recognized while impaired 441us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
511us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalWithRelatedAllowanceMember
 
Total Commercial      
Financing Receivable, Impaired [Line Items]      
Recorded Investment 32,116us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
45,652us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
 
Unpaid Principal Balance 32,116us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
45,673us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
 
Related Allowance 488us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
4,072us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
 
Average Impaired Balance 31,743us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
42,714us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
 
Interest Income Recognized while impaired 1,199us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
1,261us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalCommercialMember
 
Total Residential Real Estate      
Financing Receivable, Impaired [Line Items]      
Recorded Investment 16,199us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
15,047us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
 
Unpaid Principal Balance 16,216us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
15,062us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
 
Related Allowance 328us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
315us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
 
Average Impaired Balance 14,864us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
14,179us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
 
Interest Income Recognized while impaired 583us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
725us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalResidentialRealEstateMember
 
Total Consumer      
Financing Receivable, Impaired [Line Items]      
Recorded Investment 84us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
46us-gaap_ImpairedFinancingReceivableRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
 
Unpaid Principal Balance 84us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
47us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
 
Related Allowance 0us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
13us-gaap_ImpairedFinancingReceivableRelatedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
 
Average Impaired Balance 36us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
37us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
 
Interest Income Recognized while impaired $ 2us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember
$ 1us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= smmf_TotalConsumerMember