XML 57 R46.htm IDEA: XBRL DOCUMENT
v3.20.2

Significant Accounting Policies Significant Accounting Policies - Impact of Adoption of New Accounting Standard Related to CECL (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Jun. 30, 2020 | Jan. 01, 2020 | Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Jan. 01, 2019 | Dec. 31, 2018
--- | --- | --- | --- | --- | --- | --- | --- | ---
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | $ 160 |  |  | $ 0 |  |  |  |
Financing Receivable, Allowance for Credit Loss | 263,475 |  |  | 132,167 |  |  |  |
Off-Balance Sheet, Credit Loss, Liability | 43,663 | $ 46,939 |  | 500 | $ 500 | $ 500 |  | $ 500
Cumulative effect of accounting change |  |  |  | (29,252) |  |  |  | (14,672)
Commercial Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 72,505 | 98,536 |  | 51,593 | 52,667 | 57,714 |  | 48,580
Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 54,631 | 40,817 |  | 37,382 | 33,346 | 25,818 |  | 29,052
Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 118,593 | 93,425 |  | 31,037 | 35,353 | 35,914 |  | 38,777
Total consumer real estate loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 10,277 | 8,998 |  | 4,113 | 4,884 | 5,637 |  | 6,103
Consumer Loan [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 7,469 | 8,285 |  | 8,042 | 10,309 | 9,846 |  | 9,620
Loans Receivable [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss | 263,475 | 250,061 |  | 132,167 | $ 136,559 | $ 134,929 |  | 132,132
Residential Mortgage Backed Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | 0 |  |  | 0 |  |  |  |
US States and Political Subdivisions Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | 160 |  |  | 0 |  |  |  |
Other Investments [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | 0 |  |  | 0 |  |  |  |
Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss | $ 160 | $ 172 |  | 0 |  |  |  |
Pre-Adoption Allowance [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | $ 51,593 |  |  |  |  |
Pre-Adoption Allowance [Member] | Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 37,382 |  |  |  |  |
Pre-Adoption Allowance [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 31,037 |  |  |  |  |
Pre-Adoption Allowance [Member] | Total consumer real estate loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 4,113 |  |  |  |  |
Pre-Adoption Allowance [Member] | Consumer Loan [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 8,042 |  |  |  |  |
Pre-Adoption Allowance [Member] | Loans Receivable [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 132,167 |  |  |  |  |
Pre-Adoption Allowance [Member] | US Treasury Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Pre-Adoption Allowance [Member] | Residential Mortgage Backed Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Pre-Adoption Allowance [Member] | US States and Political Subdivisions Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Pre-Adoption Allowance [Member] | Other Investments [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Pre-Adoption Allowance [Member] | Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Pre-Adoption Allowance [Member] | Commitments to Extend Credit [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Off-Balance Sheet, Credit Loss, Liability |  |  | 500 |  |  |  |  |
Impact of Adoption [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 21,263 |  |  |  |  |
Impact of Adoption [Member] | Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | (10,453) |  |  |  |  |
Impact of Adoption [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | (13,519) |  |  |  |  |
Impact of Adoption [Member] | Total consumer real estate loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 2,392 |  |  |  |  |
Impact of Adoption [Member] | Consumer Loan [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | (2,248) |  |  |  |  |
Impact of Adoption [Member] | Loans Receivable [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | (2,565) |  |  |  |  |
Impact of Adoption [Member] | US Treasury Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Impact of Adoption [Member] | Residential Mortgage Backed Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Impact of Adoption [Member] | US States and Political Subdivisions Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 215 |  |  |  |  |
Impact of Adoption [Member] | Other Investments [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Impact of Adoption [Member] | Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 215 |  |  |  |  |
Impact of Adoption [Member] | Commitments to Extend Credit [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Off-Balance Sheet, Credit Loss, Liability |  |  | 39,377 |  |  |  |  |
Post-Adoption Allowance [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 72,856 |  |  |  |  |
Post-Adoption Allowance [Member] | Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 26,929 |  |  |  |  |
Post-Adoption Allowance [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 17,518 |  |  |  |  |
Post-Adoption Allowance [Member] | Total consumer real estate loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 6,505 |  |  |  |  |
Post-Adoption Allowance [Member] | Consumer Loan [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 5,794 |  |  |  |  |
Post-Adoption Allowance [Member] | Loans Receivable [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss |  |  | 129,602 |  |  |  |  |
Post-Adoption Allowance [Member] | US Treasury Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Post-Adoption Allowance [Member] | Residential Mortgage Backed Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Post-Adoption Allowance [Member] | US States and Political Subdivisions Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 215 |  |  |  |  |
Post-Adoption Allowance [Member] | Other Investments [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 0 |  |  |  |  |
Post-Adoption Allowance [Member] | Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Securities, held-to-maturity, allowance for credit loss |  |  | 215 |  |  |  |  |
Post-Adoption Allowance [Member] | Commitments to Extend Credit [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Off-Balance Sheet, Credit Loss, Liability |  |  | 39,877 |  |  |  |  |
Retained Earnings [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | (29,300) | $ (29,252) |  |  | $ (14,700) | $ (14,672)
Retained Earnings [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | (16,798) |  |  |  |  |
Retained Earnings [Member] | Commercial and Industrial Total Energy Loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | 8,258 |  |  |  |  |
Retained Earnings [Member] | Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | 10,680 |  |  |  |  |
Retained Earnings [Member] | Total consumer real estate loans [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | (1,890) |  |  |  |  |
Retained Earnings [Member] | Consumer Loan [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | 1,776 |  |  |  |  |
Retained Earnings [Member] | Loans Receivable [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | 2,026 |  |  |  |  |
Retained Earnings [Member] | US Treasury Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  |
Retained Earnings [Member] | Residential Mortgage Backed Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  |
Retained Earnings [Member] | US States and Political Subdivisions Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | (170) |  |  |  |  |
Retained Earnings [Member] | Other Investments [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  |
Retained Earnings [Member] | Debt Securities [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | (170) |  |  |  |  |
Retained Earnings [Member] | Commitments to Extend Credit [Member] |  |  |  |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of accounting change |  |  | $ (31,108) |  |  |  |  |

X
- Definition New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity, Net of Tax + References No definition available. + Details
Name: | cfr_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityNetOfTax
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aaa) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)(2)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82919202-210446 + Details
Name: | us-gaap_OffBalanceSheetCreditLossLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cfr_CommercialandIndustrialTotalEnergyLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cfr_TotalconsumerrealestateloansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_LoansReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
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=us-gaap_OtherInvestmentsMember
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: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=cfr_PreAdoptionAllowanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201613Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=cfr_PostAdoptionAllowanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |