Amortization term of agriculture loans if 80% of loan-to-value ratio.

No definition available.

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- Definition

Amortization term of agriculture loans if 75% of loan-to-value ratio.

+ References

No definition available.

+ Details

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- Definition

Represents the amount of loans, for which a modification had been agreed to.

+ References

No definition available.

+ Details

Name:	smbc_AmountOfLoansModifiedForOtherThanTdr
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the average term of construction loan.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
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- Definition

Maturities of construction loans related to multi family and commercial residential real estate.

+ References

No definition available.

+ Details

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- Definition

Maturities of construction loans related to single family residential real estate.

+ References

No definition available.

+ Details

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- Definition

Amortization term of fixed-rate and adjustable rate mortgage loans.

+ References

No definition available.

+ Details

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- Definition

Represents the incremental period that the loan maturity can be extended to.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
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- Definition

Term of adjusted interest rate applicability on loans.

+ References

No definition available.

+ Details

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- Definition

Amortization term of loans.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Percentage of appraised value or purchase price that loans cannot exceed.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Term of fixed interest rate applicability on loans

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the pure numeric value of Number of Loans Modified for Other Than TDR, as of the indicated date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents amount of expense (credit) related to estimated loss from loan and lease transactions, including off-balance sheet credit loss.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortization term of multi family residences loans if the balloon maturities.

+ References

No definition available.

+ Details

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Namespace Prefix:	smbc_
Data Type:	xbrli:durationItemType
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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Data Type:	na
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- Details

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- Details

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- Details

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Loans and Allowance for Credit Losses - Classes of loans information (Details)	3 Months Ended		6 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2022 USD ($)
Provision for credit losses, credit (charges)	$ 1,100,000	$ 0	$ 6,200,000	$ 305,000
Residential Real Estate.
Fixed-rate and adjustable-rate mortgage (ARM) loans amortization period (in years)			30 years
Residential Real Estate. \| Single Family
Maximum percentage of appraised value or purchase price that loans cannot exceed			90.00%
Residential Real Estate. \| Multifamily
Amortization period of loans			25 years
Amortization period of multi-family residential loans if balloon maturities			10 years
Commercial
Amortization period of loans			25 years
Term of fixed interest applicability on loans			10 years
Term of variable interest applicability on loans			7 years
Agricultural real estate terms if 80% loan-to-value ratio			25 years
Agricultural real estate terms if 75% loan-to-value ratio			30 years
Residential Real Estate
Amortization period of loans			30 years
Residential Real Estate \| Minimum
Maturities of single-family residential construction loans			6 months
Residential Real Estate \| Maximum
Maturities of single-family residential construction loans			12 months
Commercial Real Estate
Amortization period of loans			25 years
Construction Real Estate
Average term of construction loans			12 months
Construction Real Estate \| Minimum
Maturities of multifamily or commercial construction loans			12 months
Construction Real Estate \| Maximum
Maturities of multifamily or commercial construction loans			36 months
Consumer loans
Amortization period of loans			66 months
Consumer loans \| Home Equity Loan
Maximum percentage of appraised value or purchase price that loans cannot exceed			100.00%
Amortization period of loans			10 years
Consumer loans \| Automobile loans
Maximum percentage of appraised value or purchase price that loans cannot exceed			100.00%
Amortization period of loans			66 months
Commercial loans
Amortization period of loans			5 years
Amortization period of multi-family residential loans if balloon maturities			1 year
Modifications for the purpose of extending the maturity date \| Construction Real Estate
Incremental period that the loan maturity can be extended to			3 months
Number of construction loans outstanding, for which a modification had been agreed to	58		58		57
Construction loans outstanding, for which a modification had been agreed to	$ 35,500,000		$ 35,500,000		$ 13,800,000