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Loans (Impaired Loans) (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid Contractual Principal Balance | $ 69,656 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance | $ 61,007 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance | $ 105,577 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Recorded Investment With No Allowance | 50,473 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment | 32,588 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment | 43,083 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Recorded Investment With Allowance | 3,118 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment | 15,874 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment | 37,314 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Total Recorded Investment | 53,591 us-gaap_ImpairedFinancingReceivableRecordedInvestment | 48,462 us-gaap_ImpairedFinancingReceivableRecordedInvestment | 80,397 us-gaap_ImpairedFinancingReceivableRecordedInvestment
Related Allowance | 1,680 us-gaap_ImpairedFinancingReceivableRelatedAllowance | 6,926 us-gaap_ImpairedFinancingReceivableRelatedAllowance | 8,237 us-gaap_ImpairedFinancingReceivableRelatedAllowance
Average Recorded Investment | 49,636 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment | 71,741 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment | 86,580 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Commercial and Industrial, Energy [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid Contractual Principal Balance | 706 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 545 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 1,255 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember
Recorded Investment With No Allowance | 636 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 531 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember
Recorded Investment With Allowance | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 1,069 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember
Total Recorded Investment | 636 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 531 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 1,069 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember
Related Allowance | 0 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 900 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember
Average Recorded Investment | 571 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 428 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember | 214 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialEnergyFinancingReceivableMember
Commercial and Industrial, Other Commercial [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid Contractual Principal Balance | 42,212 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 31,429 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 56,784 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember
Recorded Investment With No Allowance | 29,007 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 15,337 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 21,709 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember
Recorded Investment With Allowance | 2,853 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 7,004 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 19,096 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember
Total Recorded Investment | 31,860 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 22,341 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 40,805 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember
Related Allowance | 1,613 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 4,140 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 4,200 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember
Average Recorded Investment | 27,154 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 34,894 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember | 42,630 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialAndIndustrialOtherCommercialFinancingReceivableMember
Commercial Real Estate, Buildings, Land and Other [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid Contractual Principal Balance | 22,919 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 27,792 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 44,652 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember
Recorded Investment With No Allowance | 17,441 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 15,697 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 19,010 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember
Recorded Investment With Allowance | 265 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 8,870 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 17,149 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember
Total Recorded Investment | 17,706 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 24,567 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 36,159 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember
Related Allowance | 67 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 2,786 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 3,137 us-gaap_ImpairedFinancingReceivableRelatedAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember
Average Recorded Investment | 20,339 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 34,633 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember | 40,258 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_CommercialRealEstateBuildingsLandAndOtherFinancingReceivableMember
Commercial Real Estate, Construction [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid Contractual Principal Balance | 3,007 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 1,497 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Recorded Investment With No Allowance | 2,793 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 1,100 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Total Recorded Investment | 2,793 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 1,100 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Average Recorded Investment | 739 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 634 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember | 1,392 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Consumer Real Estate [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid Contractual Principal Balance | 812 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 907 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 961 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember
Recorded Investment With No Allowance | 596 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 745 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 864 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember
Total Recorded Investment | 596 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 745 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 864 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember
Average Recorded Investment | 674 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 804 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember | 1,617 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerRealEstateFinancingReceivableMember
Consumer and Other [Member] |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Unpaid Contractual Principal Balance | 0 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | 334 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | 428 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember
Recorded Investment With No Allowance | 0 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | 278 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | 400 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember
Total Recorded Investment | 0 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | 278 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | 400 us-gaap_ImpairedFinancingReceivableRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember
Average Recorded Investment | $ 159 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | $ 348 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember | $ 469 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cfr_ConsumerAndOtherFinancingReceivableMember

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Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
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Data Type: | na
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