XML 63 R54.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands | Sep. 30, 2022 | Dec. 31, 2021
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | $ 6,657,214 | $ 8,581,829
Unrealized Loss, Less than 12 months | 534,096 | 118,680
Fair Value, Greater than 12 months | 5,823,641 | 465,833
Unrealized Loss, Greater than 12 months | 1,010,292 | 14,249
Debt Securities, Available-for-sale, Unrealized Loss Position | 12,480,855 | 9,047,662
Unrealized Loss on AFS Debt Securities | 1,544,388 | 132,929
U.S. government and federal agency obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 695,272 | 296,492
Unrealized Loss, Less than 12 months | 33,081 | 2,241
Fair Value, Greater than 12 months | 283,593 | 0
Unrealized Loss, Greater than 12 months | 15,579 | 0
Debt Securities, Available-for-sale, Unrealized Loss Position | 978,865 | 296,492
Unrealized Loss on AFS Debt Securities | 48,660 | 2,241
Government-sponsored enterprise obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 29,954 | 0
Unrealized Loss, Less than 12 months | 5,964 | 0
Fair Value, Greater than 12 months | 13,221 | 18,899
Unrealized Loss, Greater than 12 months | 6,598 | 919
Debt Securities, Available-for-sale, Unrealized Loss Position | 43,175 | 18,899
Unrealized Loss on AFS Debt Securities | 12,562 | 919
State and Municipal Obligations |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 1,101,122 | 876,691
Unrealized Loss, Less than 12 months | 72,473 | 15,874
Fair Value, Greater than 12 months | 673,390 | 32,684
Unrealized Loss, Greater than 12 months | 145,337 | 1,049
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,774,512 | 909,375
Unrealized Loss on AFS Debt Securities | 217,810 | 16,923
Agency mortgage-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 1,970,947 | 3,333,691
Unrealized Loss, Less than 12 months | 241,074 | 59,044
Fair Value, Greater than 12 months | 2,450,227 | 265,835
Unrealized Loss, Greater than 12 months | 544,264 | 8,720
Debt Securities, Available-for-sale, Unrealized Loss Position | 4,421,174 | 3,599,526
Unrealized Loss on AFS Debt Securities | 785,338 | 67,764
Non-Agency Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 417,434 | 1,285,611
Unrealized Loss, Less than 12 months | 63,282 | 17,222
Fair Value, Greater than 12 months | 811,318 | 1,948
Unrealized Loss, Greater than 12 months | 150,299 | 19
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,228,752 | 1,287,559
Unrealized Loss on AFS Debt Securities | 213,581 | 17,241
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 2,145,330 | 2,518,935
Unrealized Loss, Less than 12 months | 92,243 | 19,201
Fair Value, Greater than 12 months | 1,381,680 | 87,893
Unrealized Loss, Greater than 12 months | 105,368 | 525
Debt Securities, Available-for-sale, Unrealized Loss Position | 3,527,010 | 2,606,828
Unrealized Loss on AFS Debt Securities | 197,611 | 19,726
Total Mortgage And Asset-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 4,533,711 | 7,138,237
Unrealized Loss, Less than 12 months | 396,599 | 95,467
Fair Value, Greater than 12 months | 4,643,225 | 355,676
Unrealized Loss, Greater than 12 months | 799,931 | 9,264
Debt Securities, Available-for-sale, Unrealized Loss Position | 9,176,936 | 7,493,913
Unrealized Loss on AFS Debt Securities | 1,196,530 | 104,731
Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Fair Value, Less than 12 months | 297,155 | 270,409
Unrealized Loss, Less than 12 months | 25,979 | 5,098
Fair Value, Greater than 12 months | 210,212 | 58,574
Unrealized Loss, Greater than 12 months | 42,847 | 3,017
Debt Securities, Available-for-sale, Unrealized Loss Position | 507,367 | 328,983
Unrealized Loss on AFS Debt Securities | $ 68,826 | $ 8,115

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27337-111563 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI https://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI https://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27337-111563 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (a)(1) -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922888-210455 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI https://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (a)(2) -URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922888-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
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 No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=cbsh_AgencyMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=cbsh_NonAgencyMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=cbsh_TotalMortgageAndAssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |