XML 81 R86.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Regulatory Matters (Actual and Required Capital Ratios) (Detail) - USD ($) $ in Thousands | Dec. 31, 2019 | Jan. 01, 2019 | Dec. 31, 2018
--- | --- | --- | ---
Cullen/Frost [Member] |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Common equity tier one to risk-weighted assets, actual, capital amount | $ 2,857,250 |  | $ 2,642,475
Common equity tier one to risk-weighted assets, actual, ratio | 12.36% |  | 12.27%
Common equity tier one to risk-weighted assets, minimum capital required basel III phase-in schedule, capital amount |  |  | $ 1,372,573
Common Equity Tier One Risk Based Capital To Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  | 4.50% | 6.375%
Common Equity Tier One Capital Required For Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 1,617,886 |  | $ 1,507,139
Common Equity Tier One Risk Based Capital To Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 7.00% |  | 7.00%
Common Equity Tier One Capital Required To Be Well Capitalized, Capital Amount | $ 1,502,323 |  | $ 1,399,486
CommonEquityTierOneCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets, Ratio | 6.50% |  | 6.50%
Tier 1 Capital to Risk-Weighted Assets, Actual, Capital Amount | $ 3,001,736 |  | $ 2,786,961
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio | 12.99% |  | 12.94%
Tier One Risk Based Capital Required For Capital Adequacy Minimum Capital Required Basel III Phase In Schedule, Capital Amount |  |  | $ 1,695,532
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  |  | 7.875%
Tier One Risk Based Capital Required For Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 1,964,576 |  | $ 1,830,098
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 8.50% |  | 8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount | $ 1,849,013 |  | $ 1,722,445
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio | 8.00% |  | 8.00%
Total Capital to Risk-Weighted Assets, Actual, Capital Amount | $ 3,367,403 |  | $ 3,152,593
Total Capital to Risk-Weighted Assets, Actual, Ratio | 14.57% | 8.00% | 14.64%
Capital Required for Capital Adequacy Minimum Capital Required Basel III Phase In Schedule, Capital Amount |  |  | $ 2,126,143
Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  |  | 9.875%
Capital Required for Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 2,426,829 |  | $ 2,260,709
Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 10.50% |  | 10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount | $ 2,311,266 |  | $ 2,153,056
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio | 10.00% |  | 10.00%
Leverage Ratio, Actual, Capital Amount | $ 3,001,736 |  | $ 2,786,961
Leverage Ratio, Actual, Ratio | 9.28% |  | 9.06%
Tier One Leverage Capital Required for Capital Adequacy Minimum Capital Required Basel III Phase In Schedule, Capital Amount |  |  | $ 1,231,028
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  |  | 4.00%
Tier One Leverage Capital Required for Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 1,293,188 |  | $ 1,231,028
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 4.00% |  | 4.00%
Leverage Ratio, Required to be Considered Well Capitalized, Capital Amount | $ 1,616,485 |  | $ 1,538,785
Leverage Ratio, Required to be Considered Well Capitalized, Ratio | 5.00% |  | 5.00%
Frost Bank [Member] |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Common equity tier one to risk-weighted assets, actual, capital amount | $ 2,958,326 |  | $ 2,743,973
Common equity tier one to risk-weighted assets, actual, ratio | 12.82% |  | 12.78%
Common equity tier one to risk-weighted assets, minimum capital required basel III phase-in schedule, capital amount |  |  | $ 1,368,701
Common Equity Tier One Risk Based Capital To Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  | 4.50% | 6.375%
Common Equity Tier One Capital Required For Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 1,615,206 |  | $ 1,502,887
Common Equity Tier One Risk Based Capital To Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 7.00% |  | 7.00%
Common Equity Tier One Capital Required To Be Well Capitalized, Capital Amount | $ 1,499,834 |  | $ 1,395,538
CommonEquityTierOneCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets, Ratio | 6.50% |  | 6.50%
Tier 1 Capital to Risk-Weighted Assets, Actual, Capital Amount | $ 2,958,326 |  | $ 2,743,973
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio | 12.82% |  | 12.78%
Tier One Risk Based Capital Required For Capital Adequacy Minimum Capital Required Basel III Phase In Schedule, Capital Amount |  |  | $ 1,690,748
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  |  | 7.875%
Tier One Risk Based Capital Required For Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 1,961,322 |  | $ 1,824,934
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 8.50% |  | 8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount | $ 1,845,950 |  | $ 1,717,585
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio | 8.00% |  | 8.00%
Total Capital to Risk-Weighted Assets, Actual, Capital Amount | $ 3,090,993 |  | $ 2,876,605
Total Capital to Risk-Weighted Assets, Actual, Ratio | 13.40% | 8.00% | 13.40%
Capital Required for Capital Adequacy Minimum Capital Required Basel III Phase In Schedule, Capital Amount |  |  | $ 2,120,144
Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  |  | 9.875%
Capital Required for Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 2,422,809 |  | $ 2,254,331
Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 10.50% |  | 10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount | $ 2,307,438 |  | $ 2,146,982
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio | 10.00% |  | 10.00%
Leverage Ratio, Actual, Capital Amount | $ 2,958,326 |  | $ 2,743,973
Leverage Ratio, Actual, Ratio | 9.15% |  | 8.93%
Tier One Leverage Capital Required for Capital Adequacy Minimum Capital Required Basel III Phase In Schedule, Capital Amount |  |  | $ 1,229,650
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Minimum Capital Required Basel III Phase In Schedule, Ratio |  |  | 4.00%
Tier One Leverage Capital Required for Capital Adequacy Minimum Capital Required Basel III Fully Phased In, Capital Amount | $ 1,292,743 |  | $ 1,229,650
Tier One Leverage Capital Required for Capital Adequacy to Average Assets Minimum Capital Required Basel III Fully Phased In, Ratio | 4.00% |  | 4.00%
Leverage Ratio, Required to be Considered Well Capitalized, Capital Amount | $ 1,615,929 |  | $ 1,537,062
Leverage Ratio, Required to be Considered Well Capitalized, Ratio | 5.00% |  | 5.00%

X
- Definition Capital Required for Capital Adequacy Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_CapitalRequiredforCapitalAdequacyMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Capital Required for Capital Adequacy Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_CapitalRequiredforCapitalAdequacyMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_CapitalRequiredforCapitalAdequacytoRiskWeightedAssetsMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_CapitalRequiredforCapitalAdequacytoRiskWeightedAssetsMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Capital Required For Capital Adequacy Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_CommonEquityTierOneCapitalRequiredForCapitalAdequacyMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Common Equity Tier One Capital Required For Capital Adequacy Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_CommonEquityTierOneCapitalRequiredForCapitalAdequacyMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition CommonEquityTierOneCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets + References No definition available. + Details
Name: | cfr_CommonEquityTierOneCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital To Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_CommonEquityTierOneRiskBasedCapitalToRiskWeightedAssetsMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Risk Based Capital To Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_CommonEquityTierOneRiskBasedCapitalToRiskWeightedAssetsMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition ExcessCommonEquityTierOneCapitalToRiskWeightedAssets + References No definition available. + Details
Name: | cfr_ExcessCommonEquityTierOneCapitalToRiskWeightedAssets
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier One Leverage Capital Required for Capital Adequacy Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_TierOneLeverageCapitalRequiredforCapitalAdequacyMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tier One Leverage Capital Required for Capital Adequacy Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_TierOneLeverageCapitalRequiredforCapitalAdequacyMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tier One Leverage Capital Required for Capital Adequacy to Average Assets Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_TierOneLeverageCapitalRequiredforCapitalAdequacytoAverageAssetsMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier One Leverage Capital Required for Capital Adequacy to Average Assets Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_TierOneLeverageCapitalRequiredforCapitalAdequacytoAverageAssetsMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier One Risk Based Capital Required For Capital Adequacy Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_TierOneRiskBasedCapitalRequiredForCapitalAdequacyMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tier One Risk Based Capital Required For Capital Adequacy Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_TierOneRiskBasedCapitalRequiredForCapitalAdequacyMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Fully Phased In + References No definition available. + Details
Name: | cfr_TierOneRiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetsMinimumCapitalRequiredBaselIIIFullyPhasedIn
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Minimum Capital Required Basel III Phase In Schedule + References No definition available. + Details
Name: | cfr_TierOneRiskBasedCapitalRequiredforCapitalAdequacytoRiskWeightedAssetsMinimumCapitalRequiredBaselIIIPhaseInSchedule
Namespace Prefix: | cfr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of total capital as defined in the regulations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 + Details
Name: | us-gaap_Capital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Total Capital divided by risk weighted assets as defined in the regulations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 + Details
Name: | us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_CommonEquityTierOneCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as well-capitalized under regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_CommonEquityTierOneCapitalRequiredToBeWellCapitalized
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_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of excess Tier 1 Risk Based Capital (which consists of the types of financial capital considered the most reliable and liquid, primarily Shareholders' equity. Examples of Tier 1 capital are common stock or unit, preferred stock or unit that is irredeemable and noncumulative, and retained earnings) divided by risk-weighted assets which are assets that are weighted for credit risk according to a formula used by the Reserve Bank. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_ExcessTierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneLeverageCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 Leverage Capital divided by average assets as defined in the regulations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 Risk Based Capital as defined in the regulations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117337116&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=cfr_CullenFrostMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=cfr_FrostBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |