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Capital Requirements - Capital Amounts and Ratios (Details) - USD ($) $ in Thousands | 12 Months Ended |
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Dec. 31, 2024 | Dec. 31, 2023
Capital Requirements |  |
Percentage of capital securities issued by trust qualifying as Tier II capital, minimum | 25.00% |
Junior subordinated deferrable interest debentures | $ 108,868 | $ 108,868
Parent Company |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 2,893,228 | $ 2,563,130
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2242% | 0.2172%
Total Capital (to Risk Weighted Assets), Actual Amount | $ 3,136,215 | $ 2,790,171
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2431 | 0.2365
Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 2,974,881 | $ 2,642,492
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2306 | 0.2239
Tier 1 Capital (to Average Assets), Actual Amount | $ 2,974,881 | $ 2,642,492
Tier 1 capital (to Average Assets), Actual Ratio (as a percent) | 0.1884 | 0.1746
Parent Company | Minimum |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 903,203 | $ 825,968
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.07% | 0.07%
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 1,354,805 | $ 1,238,952
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.105 | 0.105
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 1,096,747 | $ 1,002,961
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.085 | 0.085
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Amount | $ 631,755 | $ 605,262
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.04 | 0.04
International Bank of Commerce Laredo |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 1,638,720 | $ 1,444,775
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.1946% | 0.1854%
Total Capital (to Risk Weighted Assets), Actual Amount | $ 1,744,057 | $ 1,542,462
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2071 | 0.1979
Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 1,638,720 | $ 1,444,775
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.1946 | 0.1854
Tier 1 Capital (to Average Assets), Actual Amount | $ 1,638,720 | $ 1,444,775
Tier 1 capital (to Average Assets), Actual Ratio (as a percent) | 0.1767 | 0.164
International Bank of Commerce Laredo | Minimum |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 589,359 | $ 545,611
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 547,262 | $ 506,639
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.07% | 0.07%
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.065% | 0.065%
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 884,039 | $ 818,416
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 841,942 | $ 779,444
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.105 | 0.105
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.10 | 0.10
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 715,651 | $ 662,527
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 673,554 | $ 623,555
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.085 | 0.085
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.08 | 0.08
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Amount | $ 370,911 | $ 352,412
Tier 1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 463,639 | $ 440,515
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.04 | 0.04
Tier 1 Capital (to Average Assets), To Be well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.05 | 0.05
International Bank of Commerce Brownsville |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 554,879 | $ 232,965
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2611% | 0.2072%
Total Capital (to Risk Weighted Assets), Actual Amount | $ 578,515 | $ 247,031
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2722 | 0.2197
Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 554,879 | $ 232,965
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2611 | 0.2072
Tier 1 Capital (to Average Assets), Actual Amount | $ 554,879 | $ 232,965
Tier 1 capital (to Average Assets), Actual Ratio (as a percent) | 0.1308 | 0.1472
International Bank of Commerce Brownsville | Minimum |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 148,761 | $ 78,718
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 138,136 | $ 73,095
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.07% | 0.07%
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.065% | 0.065%
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 223,142 | $ 118,076
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 212,516 | $ 112,454
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.105 | 0.105
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.10 | 0.10
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 180,639 | $ 95,586
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 170,013 | $ 89,963
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.085 | 0.085
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.08 | 0.08
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Amount | $ 169,680 | $ 63,294
Tier 1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 212,100 | $ 79,117
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.04 | 0.04
Tier 1 Capital (to Average Assets), To Be well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.05 | 0.05
International Bank Of Commerce Oklahoma |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 240,023 | $ 477,390
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2057% | 0.2441%
Total Capital (to Risk Weighted Assets), Actual Amount | $ 254,659 | $ 500,268
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2182 | 0.2558
Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 240,023 | $ 477,390
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.2057 | 0.2441
Tier 1 Capital (to Average Assets), Actual Amount | $ 240,023 | $ 477,390
Tier 1 capital (to Average Assets), Actual Ratio (as a percent) | 0.1447 | 0.1179
International Bank Of Commerce Oklahoma | Minimum |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 81,679 | $ 136,883
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 75,845 | $ 127,106
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.07% | 0.07%
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.065% | 0.065%
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 122,519 | $ 205,325
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 116,685 | $ 195,547
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.105 | 0.105
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.10 | 0.10
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 99,182 | $ 166,215
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 93,348 | $ 156,438
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.085 | 0.085
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.08 | 0.08
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Amount | $ 66,341 | $ 161,919
Tier 1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 82,926 | $ 202,398
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.04 | 0.04
Tier 1 Capital (to Average Assets), To Be well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.05 | 0.05
Commerce Bank |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 102,200 | $ 64,110
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.375% | 0.3118%
Total Capital (to Risk Weighted Assets), Actual Amount | $ 105,090 |
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.3856 | 0.3243
Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 102,200 | $ 66,680
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.375 | 0.3118
Tier 1 Capital (to Average Assets), Actual Amount | $ 102,200 | $ 64,110
Tier 1 capital (to Average Assets), Actual Ratio (as a percent) | 0.1353 | 0.1326
Commerce Bank | Minimum |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 19,077 | $ 14,394
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 17,714 | $ 13,366
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.07% | 0.07%
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.065% | 0.065%
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 28,616 | $ 21,591
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 27,253 | $ 20,563
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.105 | 0.105
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.10 | 0.10
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 23,165 | $ 17,478
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 21,802 | $ 16,450
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.085 | 0.085
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.08 | 0.08
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Amount | $ 30,219 | $ 19,338
Tier 1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 37,774 | $ 24,172
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.04 | 0.04
Tier 1 Capital (to Average Assets), To Be well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.05 | 0.05
International Bank of Commerce Zapata |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 66,932 | $ 97,334
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.3274% | 0.3657%
Total Capital (to Risk Weighted Assets), Actual Amount | $ 69,278 | $ 100,660
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.3389 | 0.3782
Tier 1 Capital (to Risk Weighted Assets), Actual Amount | $ 66,932 | $ 97,334
Tier 1 capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 0.3274 | 0.3657
Tier 1 Capital (to Average Assets), Actual Amount | $ 66,932 | $ 97,334
Tier 1 capital (to Average Assets), Actual Ratio (as a percent) | 0.1344 | 0.145
International Bank of Commerce Zapata | Minimum |  |
Capital Requirements |  |
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 14,310 | $ 18,628
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 13,287 | $ 17,298
Common Equity Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.07% | 0.07%
Common Equity Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.065% | 0.065%
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 21,464 | $ 27,943
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 20,442 | $ 26,612
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.105 | 0.105
Total Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.10 | 0.10
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Amount | $ 17,376 | $ 22,620
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 16,354 | $ 21,290
Tier 1 Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.085 | 0.085
Tier 1 Capital (to Risk Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.08 | 0.08
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Amount | $ 19,917 | $ 26,858
Tier 1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount | $ 24,896 | $ 33,572
Tier 1 Capital (to Average Assets), For Capital Adequacy Purposes Ratio (as a percent) | 0.04 | 0.04
Tier 1 Capital (to Average Assets), To Be well Capitalized Under Prompt Corrective Action Provisions Ratio (as a percent) | 0.05 | 0.05

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- Definition Amount of total capital as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1 + Details
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