XML 64 R53.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Loans and Allowance for Credit Losses - Credit risk profile based on rating category and year of origination (Details) - USD ($) $ in Thousands | 6 Months Ended |
--- | --- | ---
Dec. 31, 2024 | Jun. 30, 2024
Financing Receivable, Credit Quality Indicator [Line Items] |  |
Amount of loan relationships subject to annual credit analysis | $ 4,000 |
Loan relationships that are subject to independent annual review | 1,000 |
2025 / 2024 | 545,108 | $ 737,190
2024 / 2023 | 572,978 | 953,922
2023 / 2022 | 901,833 | 833,645
2022 / 2021 | 779,144 | 518,406
2021 / 2020 | 448,789 | 171,485
Prior | 329,328 | 200,743
Revolving loans | 450,001 | 434,644
Total | 4,027,181 | 3,850,035
Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 528,091 | 720,679
2024 / 2023 | 564,116 | 926,158
2023 / 2022 | 877,917 | 802,592
2022 / 2021 | 749,376 | 515,857
2021 / 2020 | 445,748 | 166,539
Prior | 323,839 | 196,262
Revolving loans | 447,499 | 432,843
Total | 3,936,586 | 3,760,930
Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 14,897 | 8,921
2024 / 2023 | 4,050 | 26,306
2023 / 2022 | 23,341 | 2,049
2022 / 2021 | 1,951 | 2,063
2021 / 2020 | 2,114 | 4,800
Prior | 3,139 | 2,963
Revolving loans | 1,521 | 1,141
Total | 51,013 | 48,243
Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 2,120 | 7,590
2024 / 2023 | 4,812 | 1,458
2023 / 2022 | 575 | 29,004
2022 / 2021 | 27,817 | 486
2021 / 2020 | 927 | 146
Prior | 2,350 | 1,518
Revolving loans | 981 | 660
Total | 39,582 | 40,862
Construction and land development |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 119,617 |
2024 / 2023 | 82,003 |
2023 / 2022 | 157,946 |
2022 / 2021 | 27,164 |
2021 / 2020 | 2,322 |
Prior | 2,444 |
Revolving loans | 1,892 |
Total | 393,388 |
Construction and land development | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 113,678 |
2024 / 2023 | 82,003 |
2023 / 2022 | 157,946 |
2022 / 2021 | 27,040 |
2021 / 2020 | 2,322 |
Prior | 2,375 |
Revolving loans | 1,892 |
Total | 387,256 |
Construction and land development | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 4,949 |
2022 / 2021 | 124 |
Prior | 69 |
Total | 5,142 |
Construction and land development | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 990 |
Total | 990 |
Agriculture real estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 24,701 |
2024 / 2023 | 36,670 |
2023 / 2022 | 42,858 |
2022 / 2021 | 52,274 |
2021 / 2020 | 46,471 |
Prior | 17,069 |
Revolving loans | 19,869 |
Total | 239,912 |
Agriculture real estate | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 24,666 |
2024 / 2023 | 34,110 |
2023 / 2022 | 42,486 |
2022 / 2021 | 52,165 |
2021 / 2020 | 46,195 |
Prior | 16,810 |
Revolving loans | 19,869 |
Total | 236,301 |
Agriculture real estate | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2024 / 2023 | 248 |
2023 / 2022 | 91 |
2022 / 2021 | 109 |
Prior | 259 |
Total | 707 |
Agriculture real estate | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 35 |
2024 / 2023 | 2,312 |
2023 / 2022 | 281 |
2021 / 2020 | 276 |
Total | 2,904 |
Commercial and industrial |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 102,680 | 117,476
2024 / 2023 | 86,511 | 60,929
2023 / 2022 | 51,853 | 44,107
2022 / 2021 | 38,342 | 43,879
2021 / 2020 | 21,051 | 3,261
Prior | 8,857 | 5,860
Revolving loans | 175,505 | 174,635
Total | 484,799 | 450,147
Commercial and industrial | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 98,595 | 116,173
2024 / 2023 | 86,134 | 60,404
2023 / 2022 | 50,804 | 43,205
2022 / 2021 | 37,339 | 43,879
2021 / 2020 | 20,757 | 3,145
Prior | 8,098 | 4,863
Revolving loans | 174,451 | 174,181
Total | 476,178 | 445,850
Commercial and industrial | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 3,988 | 1,031
2024 / 2023 | 200 | 250
2023 / 2022 | 847 | 43
2022 / 2021 | 37 |
2021 / 2020 | 255 |
Prior | 16 | 228
Revolving loans | 804 | 404
Total | 6,147 | 1,956
Commercial and industrial | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 97 | 272
2024 / 2023 | 177 | 275
2023 / 2022 | 202 | 859
2022 / 2021 | 966 |
2021 / 2020 | 39 | 116
Prior | 743 | 769
Revolving loans | 250 | 50
Total | 2,474 | 2,341
Agriculture production |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 20,646 | 41,155
2024 / 2023 | 32,125 | 11,348
2023 / 2022 | 9,818 | 4,328
2022 / 2021 | 3,642 | 6,176
2021 / 2020 | 5,699 | 1,965
Prior | 2,068 | 383
Revolving loans | 114,286 | 110,613
Total | 188,284 | 175,968
Agriculture production | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 20,471 | 40,980
2024 / 2023 | 32,054 | 11,288
2023 / 2022 | 9,814 | 4,115
2022 / 2021 | 3,642 | 6,159
2021 / 2020 | 5,682 | 1,965
Prior | 2,056 | 229
Revolving loans | 114,069 | 110,396
Total | 187,788 | 175,132
Agriculture production | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 137 | 170
2024 / 2023 | 71 | 37
2023 / 2022 |  | 204
Prior |  | 127
Revolving loans | 217 | 217
Total | 425 | 755
Agriculture production | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 38 | 5
2024 / 2023 |  | 23
2023 / 2022 | 4 | 9
2022 / 2021 |  | 17
2021 / 2020 | 17 |
Prior | 12 | 27
Total | 71 | 81
Consumer |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 17,686 | 30,317
2024 / 2023 | 17,952 | 17,321
2023 / 2022 | 12,271 | 6,558
2022 / 2021 | 4,615 | 2,271
2021 / 2020 | 1,468 | 467
Prior | 271 | 54
Revolving loans | 1,754 | 2,683
Total | 56,017 | 59,671
Consumer | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 17,680 | 30,317
2024 / 2023 | 17,925 | 17,318
2023 / 2022 | 12,255 | 6,547
2022 / 2021 | 4,614 | 2,268
2021 / 2020 | 1,438 | 467
Prior | 271 | 54
Revolving loans | 1,754 | 2,683
Total | 55,937 | 59,654
Consumer | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 6 |
2024 / 2023 | 27 | 3
2023 / 2022 | 16 | 11
2022 / 2021 | 1 | 3
2021 / 2020 | 30 |
Total | 80 | 17
All other loans |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 131 | 1,139
2024 / 2023 | 1,000 | 644
2023 / 2022 | 578 | 122
2022 / 2021 | 82 | 217
2021 / 2020 | 210 | 43
Prior | 1,627 | 1,816
Total | 3,628 | 3,981
All other loans | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 131 | 1,139
2024 / 2023 | 1,000 | 644
2023 / 2022 | 578 | 122
2022 / 2021 | 82 | 217
2021 / 2020 | 210 | 43
Prior | 1,627 | 1,816
Total | 3,628 | 3,981
Secured by real estate | 1-4 residential real estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 120,888 | 169,297
2024 / 2023 | 136,957 | 158,616
2023 / 2022 | 144,112 | 195,332
2022 / 2021 | 179,625 | 143,300
2021 / 2020 | 134,037 | 66,420
Prior | 145,367 | 93,045
Revolving loans | 106,210 | 99,387
Total | 967,196 | 925,397
Secured by real estate | 1-4 residential real estate | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 119,788 | 167,734
2024 / 2023 | 135,773 | 157,530
2023 / 2022 | 143,747 | 195,002
2022 / 2021 | 178,615 | 142,721
2021 / 2020 | 133,271 | 66,292
Prior | 143,936 | 92,728
Revolving loans | 105,962 | 99,365
Total | 961,092 | 921,372
Secured by real estate | 1-4 residential real estate | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 146 | 877
2024 / 2023 | 690 | 289
2023 / 2022 | 335 | 87
2022 / 2021 | 328 | 396
2021 / 2020 | 201 | 98
Prior | 261 | 23
Total | 1,961 | 1,770
Secured by real estate | 1-4 residential real estate | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 954 | 686
2024 / 2023 | 494 | 797
2023 / 2022 | 30 | 243
2022 / 2021 | 682 | 183
2021 / 2020 | 565 | 30
Prior | 1,170 | 294
Revolving loans | 248 | 22
Total | 4,143 | 2,255
Secured by real estate | Commercial Real Estate | Non-owner occupied |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 56,535 | 125,572
2024 / 2023 | 100,675 | 249,077
2023 / 2022 | 240,004 | 320,030
2022 / 2021 | 309,186 | 103,893
2021 / 2020 | 86,306 | 38,134
Prior | 81,580 | 56,594
Revolving loans | 8,198 | 6,470
Total | 882,484 | 899,770
Secured by real estate | Commercial Real Estate | Non-owner occupied | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 51,464 | 120,914
2024 / 2023 | 98,905 | 232,802
2023 / 2022 | 224,508 | 294,138
2022 / 2021 | 283,746 | 102,380
2021 / 2020 | 84,796 | 33,691
Prior | 80,202 | 55,190
Revolving loans | 8,198 | 6,470
Total | 831,819 | 845,585
Secured by real estate | Commercial Real Estate | Non-owner occupied | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 5,071 | 4,658
2024 / 2023 | 1,770 | 16,232
2023 / 2022 | 15,454 | 209
2022 / 2021 | 202 | 1,513
2021 / 2020 | 1,510 | 4,443
Prior | 1,378 | 1,404
Total | 25,385 | 28,459
Secured by real estate | Commercial Real Estate | Non-owner occupied | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2024 / 2023 |  | 43
2023 / 2022 | 42 | 25,683
2022 / 2021 | 25,238 |
Total | 25,280 | 25,726
Secured by real estate | Commercial Real Estate | Owner occupied |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 38,073 | 67,736
2024 / 2023 | 59,482 | 105,268
2023 / 2022 | 94,602 | 92,738
2022 / 2021 | 86,927 | 87,129
2021 / 2020 | 79,519 | 25,664
Prior | 55,627 | 27,733
Revolving loans | 21,162 | 21,208
Total | 435,392 | 427,476
Secured by real estate | Commercial Real Estate | Owner occupied | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 37,467 | 63,251
2024 / 2023 | 56,609 | 98,776
2023 / 2022 | 87,988 | 89,361
2022 / 2021 | 84,846 | 86,975
2021 / 2020 | 79,371 | 25,664
Prior | 54,046 | 26,124
Revolving loans | 20,179 | 20,147
Total | 420,506 | 410,298
Secured by real estate | Commercial Real Estate | Owner occupied | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 606 | 1,252
2024 / 2023 | 1,071 | 6,492
2023 / 2022 | 6,614 | 1,178
2022 / 2021 | 1,151 | 154
2021 / 2020 | 148 |
Prior | 1,156 | 1,181
Revolving loans | 500 | 520
Total | 11,246 | 10,777
Secured by real estate | Commercial Real Estate | Owner occupied | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 3,233
2024 / 2023 | 1,802 |
2023 / 2022 |  | 2,199
2022 / 2021 | 930 |
Prior | 425 | 428
Revolving loans | 483 | 541
Total | 3,640 | 6,401
Secured by real estate | Multi-family real estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 44,151 | 36,518
2024 / 2023 | 19,603 | 157,471
2023 / 2022 | 147,791 | 86,171
2022 / 2021 | 77,287 | 77,545
2021 / 2020 | 71,706 | 21,438
Prior | 14,418 | 5,341
Revolving loans | 1,125 | 80
Total | 376,081 | 384,564
Secured by real estate | Multi-family real estate | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 | 44,151 | 36,518
2024 / 2023 | 19,603 | 157,471
2023 / 2022 | 147,791 | 86,171
2022 / 2021 | 77,287 | 77,545
2021 / 2020 | 71,706 | 21,438
Prior | 14,418 | 5,341
Revolving loans | 1,125 | 80
Total | 376,081 | 384,564
Secured by real estate | Construction and land development |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 105,943
2024 / 2023 |  | 146,480
2023 / 2022 |  | 27,655
2022 / 2021 |  | 4,379
2021 / 2020 |  | 3,887
Prior |  | 679
Revolving loans |  | 1,518
Total | 393,388 | 290,541
Secured by real estate | Construction and land development | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 104,162
2024 / 2023 |  | 143,538
2023 / 2022 |  | 27,524
2022 / 2021 |  | 4,379
2021 / 2020 |  | 3,887
Prior |  | 679
Revolving loans |  | 1,518
Total |  | 285,687
Secured by real estate | Construction and land development | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 652
2024 / 2023 |  | 2,906
2023 / 2022 |  | 131
Total |  | 3,689
Secured by real estate | Construction and land development | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 1,129
2024 / 2023 |  | 36
Total |  | 1,165
Secured by real estate | Agriculture real estate |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 42,037
2024 / 2023 |  | 46,768
2023 / 2022 |  | 56,604
2022 / 2021 |  | 49,617
2021 / 2020 |  | 10,206
Prior |  | 9,238
Revolving loans |  | 18,050
Total | $ 239,912 | 232,520
Secured by real estate | Agriculture real estate | Pass |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 39,491
2024 / 2023 |  | 46,387
2023 / 2022 |  | 56,407
2022 / 2021 |  | 49,334
2021 / 2020 |  | 9,947
Prior |  | 9,238
Revolving loans |  | 18,003
Total |  | 228,807
Secured by real estate | Agriculture real estate | Watch |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 281
2024 / 2023 |  | 100
2023 / 2022 |  | 197
2021 / 2020 |  | 259
Total |  | 837
Secured by real estate | Agriculture real estate | Substandard |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |
2025 / 2024 |  | 2,265
2024 / 2023 |  | 281
2022 / 2021 |  | 283
Revolving loans |  | 47
Total |  | $ 2,876

X
- Definition Represents the minimum amount of total loan relationships that are subject to independent annual review. + References No definition available. + Details
Name: | smbc_CreditQualityIndicatorsMinimumLoanRelationshipsSubjectToIndependentLoanReview
Namespace Prefix: | smbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the minimum amount of loan relationships which are subject to annual credit analysis. + References No definition available. + Details
Name: | smbc_CreditQualityIndicatorsThresholdOfLendingRelationshipsAnnualCreditAnalysis
Namespace Prefix: | smbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest, before allowance for credit loss, fee, after loan in process, of financing receivable. Excludes net investment in leases. + References No definition available. + Details
Name: | smbc_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAfterLoanInProcess
Namespace Prefix: | smbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestRevolving
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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 Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 29 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-29 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-5 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_CriticizedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=smbc_ConstructionPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=smbc_AgricultureRealEstatePortfolioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=smbc_CommercialAndIndustrialPortfolioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=smbc_AgricultureProductionPortfolioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=srt_OtherPropertyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_RealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=srt_SingleFamilyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=us-gaap_CommercialBorrowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfFinancingReceivableTypeOfBorrowerAxis=us-gaap_ConsumerBorrowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=srt_MultifamilyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |