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v2.4.1.9

Note 9 - Borrowed Funds (Details) (USD $) | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2015 | Dec. 31, 2014 | Mar. 31, 2014
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Securities Sold under Agreements to Repurchase | 400,000,000 us-gaap_SecuritiesSoldUnderAgreementsToRepurchase | $ 450,000,000 us-gaap_SecuritiesSoldUnderAgreementsToRepurchase |
Weighted Average Rate of Securities Sold Under Agreements | 3.89%caty_WeightedAverageRateOfSecuritiesSoldUnderAgreements | 3.85%caty_WeightedAverageRateOfSecuritiesSoldUnderAgreements |
Prepaid Security Sold Under Repurchase Agreement |  |  | 100,000,000 caty_PrepaidSecuritySoldUnderRepurchaseAgreement
Rate of Prepaid Security Sold Under Repurchase Agreements |  |  | 3.50%caty_RateOfPrepaidSecuritySoldUnderRepurchaseAgreements
Prepayment Penalty Security Sold Under Agreements to Repurchase |  |  | 3,400,000 caty_PrepaymentPenaltySecuritySoldUnderAgreementsToRepurchase
Federal Home Loan Bank, Advances, Maturities Summary, Due in Next Twelve Months | 460,000,000 us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate | 400,000,000 us-gaap_FederalHomeLoanBankAdvancesMaturitiesSummaryDueWithinOneYearOfBalanceSheetDate |
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Interest Rate | 0.24%us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankInterestRate | 0.27%us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankInterestRate |
Long-term Federal Home Loan Bank Advances | 25,000,000 us-gaap_FederalHomeLoanBankAdvancesLongTerm | 25,000,000 us-gaap_FederalHomeLoanBankAdvancesLongTerm |
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Weighted Average Interest Rate | 1.13%us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankWeightedAverageInterestRate | 1.13%us-gaap_FederalHomeLoanBankAdvancesBranchOfFHLBBankWeightedAverageInterestRate |
Callable Securities [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Number of Floating-to-fixed Rate Agreements | 4 caty_NumberOfFloatingToFixedRateAgreements / us-gaap_FinancialInstrumentAxis = caty_CallableSecuritiesMember |  |
Non Callable Fixed Rate Securities [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Securities Sold under Agreements to Repurchase | 200,000,000 us-gaap_SecuritiesSoldUnderAgreementsToRepurchase / us-gaap_FinancialInstrumentAxis = caty_NonCallableFixedRateSecuritiesMember |  |
Weighted Average Rate of Securities Sold Under Agreements | 2.78%caty_WeightedAverageRateOfSecuritiesSoldUnderAgreements / us-gaap_FinancialInstrumentAxis = caty_NonCallableFixedRateSecuritiesMember |  |
Mature in August 2016 [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Two | 50,000,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo / us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis = caty_MatureInAugust2016Member |  |
Mature in July 2017 [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Three | 50,000,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree / us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis = caty_MatureInJuly2017Member |  |
Mature in June 2018 [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Four | 50,000,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour / us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis = caty_MatureInJune2018Member |  |
Mature in July 2018 [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Long-term Debt, Maturities, Repayments of Principal in Year Five | 50,000,000 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive / us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis = caty_MatureInJuly2018Member |  |
Floating to Fixed Rate Agreements Totaling $200 Million [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Debt Instrument, Basis Spread on Variable Rate | 3.40%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / caty_FinancialInstrumentsOwnedAxis = caty_FloatingToFixedRateAgreementsTotaling200MillionMember / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |
Floating to Fixed Rate Agreements Totaling $200 Million [Member] | Maximum [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.07%us-gaap_DebtInstrumentInterestRateStatedPercentage / caty_FinancialInstrumentsOwnedAxis = caty_FloatingToFixedRateAgreementsTotaling200MillionMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |
Floating to Fixed Rate Agreements Totaling $200 Million [Member] | Minimum [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.89%us-gaap_DebtInstrumentInterestRateStatedPercentage / caty_FinancialInstrumentsOwnedAxis = caty_FloatingToFixedRateAgreementsTotaling200MillionMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Floating to Fixed Rate Agreements Totaling $200 Million [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Number of Floating-to-fixed Rate Agreements | 4 caty_NumberOfFloatingToFixedRateAgreements / caty_FinancialInstrumentsOwnedAxis = caty_FloatingToFixedRateAgreementsTotaling200MillionMember |  |
Total Floating to Fixed Rate | 200,000,000 caty_TotalFloatingToFixedRate / caty_FinancialInstrumentsOwnedAxis = caty_FloatingToFixedRateAgreementsTotaling200MillionMember |  |
Debt, Weighted Average Interest Rate | 5.00%us-gaap_DebtWeightedAverageInterestRate / caty_FinancialInstrumentsOwnedAxis = caty_FloatingToFixedRateAgreementsTotaling200MillionMember |  |
Floating Interest Rate, Range of Time Period | 1 year |  |
Securities Sold under Agreements to Repurchase [Member] |  |  |
Note 9 - Borrowed Funds (Details) [Line Items] |  |  |
Investment Securities Pledged As Collateral | 467,500,000 caty_InvestmentSecuritiesPledgedAsCollateral / caty_FinancialInstrumentsOwnedAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember | $ 516,300,000 caty_InvestmentSecuritiesPledgedAsCollateral / caty_FinancialInstrumentsOwnedAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember |

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