3.25.4 html 694 658 1 true 127 0 false 4 false false R1.htm 000 - Document - Document And Entity Information Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-document-and-entity-information Document And Entity Information Cover 1 false false R2.htm 001 - Statement - Consolidated Balance Sheets Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-consolidated-balance-sheets Consolidated Balance Sheets Statements 2 false false R3.htm 002 - Statement - Consolidated Balance Sheets (Parentheticals) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-consolidated-balance-sheets-parentheticals Consolidated Balance Sheets (Parentheticals) Statements 3 false false R4.htm 003 - Statement - Consolidated Statements of Operations and Comprehensive Income Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-consolidated-statements-of-operations-and-comprehensive-income Consolidated Statements of Operations and Comprehensive Income Statements 4 false false R5.htm 004 - Statement - Consolidated Statements of Changes in Stockholders' Equity Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-consolidated-statements-of-changes-in-stockholders-equity- Consolidated Statements of Changes in Stockholders' Equity Statements 5 false false R6.htm 005 - Statement - Consolidated Statements of Changes in Stockholders' Equity (Parentheticals) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-consolidated-statements-of-changes-in-stockholders-equity-parentheticals Consolidated Statements of Changes in Stockholders' Equity (Parentheticals) Statements 6 false false R7.htm 006 - Statement - Consolidated Statements of Cash Flows Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-consolidated-statements-of-cash-flows Consolidated Statements of Cash Flows Statements 7 false false R8.htm 995443 - Disclosure - Award Timing Disclosure Sheet http://xbrl.sec.gov/ecd/role/AwardTimingDisclosure Award Timing Disclosure Notes 8 false false R9.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 9 false false R10.htm 995447 - Disclosure - Insider Trading Policies and Procedures Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc Insider Trading Policies and Procedures Notes 10 false false R11.htm 995550 - Disclosure - Cybersecurity Risk Management and Strategy Disclosure Sheet http://xbrl.sec.gov/cyd/role/CybersecurityRiskManagementAndStrategyDisclosure Cybersecurity Risk Management and Strategy Disclosure Notes 11 false false R12.htm 995555 - Disclosure - Note 1 - Summary of Significant Accounting Policies Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-1-summary-of-significant-accounting-policies Note 1 - Summary of Significant Accounting Policies Notes 12 false false R13.htm 995556 - Disclosure - Note 2 - Cash, Cash Equivalents and Restricted Cash Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-2-cash-cash-equivalents-and-restricted-cash Note 2 - Cash, Cash Equivalents and Restricted Cash Notes 13 false false R14.htm 995557 - Disclosure - Note 3 - Investment Securities Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities Note 3 - Investment Securities Notes 14 false false R15.htm 995558 - Disclosure - Note 4 - Loans Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans Note 4 - Loans Notes 15 false false R16.htm 995559 - Disclosure - Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships Notes 16 false false R17.htm 995560 - Disclosure - Note 6 - Premises and Equipment Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-6-premises-and-equipment Note 6 - Premises and Equipment Notes 17 false false R18.htm 995561 - Disclosure - Note 7 - Goodwill and Other Intangible Assets Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-7-goodwill-and-other-intangible-assets Note 7 - Goodwill and Other Intangible Assets Notes 18 false false R19.htm 995562 - Disclosure - Note 8 - Deposits Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits Note 8 - Deposits Notes 19 false false R20.htm 995563 - Disclosure - Note 9 - Borrowed Funds Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-9-borrowed-funds Note 9 - Borrowed Funds Notes 20 false false R21.htm 995564 - Disclosure - Note 10 - Capital Resources Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-10-capital-resources Note 10 - Capital Resources Notes 21 false false R22.htm 995565 - Disclosure - Note 11 - Income Taxes Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes Note 11 - Income Taxes Notes 22 false false R23.htm 995566 - Disclosure - Note 12 - Stockholders' Equity and Earnings Per Share Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-12-stockholders-equity-and-earnings-per-share Note 12 - Stockholders' Equity and Earnings Per Share Notes 23 false false R24.htm 995567 - Disclosure - Note 13 - Commitments and Contingencies Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-13-commitments-and-contingencies Note 13 - Commitments and Contingencies Notes 24 false false R25.htm 995568 - Disclosure - Note 14 - Leases Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-14-leases Note 14 - Leases Notes 25 false false R26.htm 995569 - Disclosure - Note 15 - Financial Derivatives Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-15-financial-derivatives Note 15 - Financial Derivatives Notes 26 false false R27.htm 995570 - Disclosure - Note 16 - Fair Value Measurements and Fair Value of Financial Instruments Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments Note 16 - Fair Value Measurements and Fair Value of Financial Instruments Notes 27 false false R28.htm 995571 - Disclosure - Note 17 - Revenue From Contracts With Clients Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-17-revenue-from-contracts-with-clients Note 17 - Revenue From Contracts With Clients Notes 28 false false R29.htm 995572 - Disclosure - Note 18 - Employee Benefit Plans Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-18-employee-benefit-plans Note 18 - Employee Benefit Plans Notes 29 false false R30.htm 995573 - Disclosure - Note 19 - Equity Incentive Plans Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-19-equity-incentive-plans Note 19 - Equity Incentive Plans Notes 30 false false R31.htm 995574 - Disclosure - Note 20 - Condensed Financial Information of Cathay General Bancorp Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-20-condensed-financial-information-of-cathay-general-bancorp Note 20 - Condensed Financial Information of Cathay General Bancorp Notes 31 false false R32.htm 995575 - Disclosure - Note 21 - Dividend Reinvestment Plan Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-21-dividend-reinvestment-plan Note 21 - Dividend Reinvestment Plan Notes 32 false false R33.htm 995576 - Disclosure - Note 22 - Regulatory Matters Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-22-regulatory-matters Note 22 - Regulatory Matters Notes 33 false false R34.htm 995577 - Disclosure - Note 23 - Balance Sheet Offsetting Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-23-balance-sheet-offsetting Note 23 - Balance Sheet Offsetting Notes 34 false false R35.htm 995578 - Disclosure - Note 24 - Subsequent Events Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-24-subsequent-events Note 24 - Subsequent Events Notes 35 false false R36.htm 995579 - Disclosure - Significant Accounting Policies (Policies) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-significant-accounting-policies-policies Significant Accounting Policies (Policies) Policies http://www.cathaygeneralbancorp.com/20251231/role/statement-note-1-summary-of-significant-accounting-policies 36 false false R37.htm 995580 - Disclosure - Note 1 - Summary of Significant Accounting Policies (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-1-summary-of-significant-accounting-policies-tables Note 1 - Summary of Significant Accounting Policies (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-1-summary-of-significant-accounting-policies 37 false false R38.htm 995581 - Disclosure - Note 3 - Investment Securities (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities-tables Note 3 - Investment Securities (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities 38 false false R39.htm 995582 - Disclosure - Note 4 - Loans (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-tables Note 4 - Loans (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans 39 false false R40.htm 995583 - Disclosure - Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships-tables Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships 40 false false R41.htm 995584 - Disclosure - Note 6 - Premises and Equipment (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-6-premises-and-equipment-tables Note 6 - Premises and Equipment (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-6-premises-and-equipment 41 false false R42.htm 995585 - Disclosure - Note 7 - Goodwill and Other Intangible Assets (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-7-goodwill-and-other-intangible-assets-tables Note 7 - Goodwill and Other Intangible Assets (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-7-goodwill-and-other-intangible-assets 42 false false R43.htm 995586 - Disclosure - Note 8 - Deposits (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits-tables Note 8 - Deposits (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits 43 false false R44.htm 995587 - Disclosure - Note 10 - Capital Resources (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-10-capital-resources-tables Note 10 - Capital Resources (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-10-capital-resources 44 false false R45.htm 995588 - Disclosure - Note 11 - Income Taxes (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes-tables Note 11 - Income Taxes (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes 45 false false R46.htm 995589 - Disclosure - Note 12 - Stockholders' Equity and Earnings Per Share (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-12-stockholders-equity-and-earnings-per-share-tables Note 12 - Stockholders' Equity and Earnings Per Share (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-12-stockholders-equity-and-earnings-per-share 46 false false R47.htm 995590 - Disclosure - Note 13 - Commitments and Contingencies (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-13-commitments-and-contingencies-tables Note 13 - Commitments and Contingencies (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-13-commitments-and-contingencies 47 false false R48.htm 995591 - Disclosure - Note 14 - Leases (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-14-leases-tables Note 14 - Leases (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-14-leases 48 false false R49.htm 995592 - Disclosure - Note 15 - Financial Derivatives (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-15-financial-derivatives-tables Note 15 - Financial Derivatives (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-15-financial-derivatives 49 false false R50.htm 995593 - Disclosure - Note 16 - Fair Value Measurements and Fair Value of Financial Instruments (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments-tables Note 16 - Fair Value Measurements and Fair Value of Financial Instruments (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments 50 false false R51.htm 995594 - Disclosure - Note 17 - Revenue From Contracts With Clients (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-17-revenue-from-contracts-with-clients-tables Note 17 - Revenue From Contracts With Clients (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-17-revenue-from-contracts-with-clients 51 false false R52.htm 995595 - Disclosure - Note 19 - Equity Incentive Plans (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-19-equity-incentive-plans-tables Note 19 - Equity Incentive Plans (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-19-equity-incentive-plans 52 false false R53.htm 995596 - Disclosure - Note 20 - Condensed Financial Information of Cathay General Bancorp (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-20-condensed-financial-information-of-cathay-general-bancorp-tables Note 20 - Condensed Financial Information of Cathay General Bancorp (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-20-condensed-financial-information-of-cathay-general-bancorp 53 false false R54.htm 995597 - Disclosure - Note 22 - Regulatory Matters (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-22-regulatory-matters-tables Note 22 - Regulatory Matters (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-22-regulatory-matters 54 false false R55.htm 995598 - Disclosure - Note 23 - Balance Sheet Offsetting (Tables) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-23-balance-sheet-offsetting-tables Note 23 - Balance Sheet Offsetting (Tables) Tables http://www.cathaygeneralbancorp.com/20251231/role/statement-note-23-balance-sheet-offsetting 55 false false R56.htm 995599 - Disclosure - Note 1 - Summary of Significant Accounting Policies (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-1-summary-of-significant-accounting-policies-details-textual Note 1 - Summary of Significant Accounting Policies (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-1-summary-of-significant-accounting-policies-tables 56 false false R57.htm 995600 - Disclosure - Note 1 - Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-1-summary-of-significant-accounting-policies-estimated-useful-lives-of-assets-details Note 1 - Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Details) Details 57 false false R58.htm 995601 - Disclosure - Note 2 - Cash, Cash Equivalents and Restricted Cash (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-2-cash-cash-equivalents-and-restricted-cash-details-textual Note 2 - Cash, Cash Equivalents and Restricted Cash (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-2-cash-cash-equivalents-and-restricted-cash 58 false false R59.htm 995602 - Disclosure - Note 3 - Investment Securities (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities-details-textual Note 3 - Investment Securities (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities-tables 59 false false R60.htm 995603 - Disclosure - Note 3 - Investment Securities - Investment Securities (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities-investment-securities-details Note 3 - Investment Securities - Investment Securities (Details) Details 60 false false R61.htm 995604 - Disclosure - Note 3 - Investment Securities - Investments by Contractual Maturity Date (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities-investments-by-contractual-maturity-date-details Note 3 - Investment Securities - Investments by Contractual Maturity Date (Details) Details 61 false false R62.htm 995605 - Disclosure - Note 3 - Investment Securities - Temporarily Impaired Securities (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-3-investment-securities-temporarily-impaired-securities-details Note 3 - Investment Securities - Temporarily Impaired Securities (Details) Details 62 false false R63.htm 995606 - Disclosure - Note 4 - Loans (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-details-textual Note 4 - Loans (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-tables 63 false false R64.htm 995607 - Disclosure - Note 4 - Loans - Components of Loans in Consolidated Balance Sheets (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-components-of-loans-in-consolidated-balance-sheets-details Note 4 - Loans - Components of Loans in Consolidated Balance Sheets (Details) Details 64 false false R65.htm 995608 - Disclosure - Note 4 - Loans - Loans to Related Parties (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-loans-to-related-parties-details Note 4 - Loans - Loans to Related Parties (Details) Details 65 false false R66.htm 995609 - Disclosure - Note 4 - Loans - Average Balance and Interest Income Recognized Related to Non-accrual Loans (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-average-balance-and-interest-income-recognized-related-to-nonaccrual-loans-details Note 4 - Loans - Average Balance and Interest Income Recognized Related to Non-accrual Loans (Details) Details 66 false false R67.htm 995610 - Disclosure - Note 4 - Loans - Nonaccrual Loans and Related Allowance for Credit Losses (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-nonaccrual-loans-and-related-allowance-for-credit-losses-details Note 4 - Loans - Nonaccrual Loans and Related Allowance for Credit Losses (Details) Details 67 false false R68.htm 995611 - Disclosure - Note 4 - Loans - Aging of Loan Portfolio (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-aging-of-loan-portfolio-details Note 4 - Loans - Aging of Loan Portfolio (Details) Details 68 false false R69.htm 995612 - Disclosure - Note 4 - Loans - Amortized Cost of Modified Loans (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-amortized-cost-of-modified-loans-details Note 4 - Loans - Amortized Cost of Modified Loans (Details) Details 69 false false R70.htm 995613 - Disclosure - Note 4 - Loans - Performance of Modified Loans (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-performance-of-modified-loans-details Note 4 - Loans - Performance of Modified Loans (Details) Details 70 false false R71.htm 995614 - Disclosure - Note 4 - Loans - Loan Held for Investment by Loan Portfolio Segments, Internal Risk Ratings and Vintage Year (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-loan-held-for-investment-by-loan-portfolio-segments-internal-risk-ratings-and-vintage-year-details Note 4 - Loans - Loan Held for Investment by Loan Portfolio Segments, Internal Risk Ratings and Vintage Year (Details) Details 71 false false R72.htm 995615 - Disclosure - Note 4 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-4-loans-allowance-for-loan-losses-by-portfolio-segment-details Note 4 - Loans - Allowance for Loan Losses by Portfolio Segment (Details) Details 72 false false R73.htm 995616 - Disclosure - Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships-details-textual Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships-tables 73 false false R74.htm 995617 - Disclosure - Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Investments in Affordable Housing and Alternative Energy Partnerships (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships-investments-in-affordable-housing-and-alternative-energy-partnerships-details Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Investments in Affordable Housing and Alternative Energy Partnerships (Details) Details 74 false false R75.htm 995618 - Disclosure - Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Unfunded Commitments Future Estimated Payments (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships-unfunded-commitments-future-estimated-payments-details Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Unfunded Commitments Future Estimated Payments (Details) Details 75 false false R76.htm 995619 - Disclosure - Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Usage of Affordable Housing and Other Tax Credits Including Energy Tax Credit (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-5-investments-in-affordable-housing-and-alternative-energy-partnerships-usage-of-affordable-housing-and-other-tax-credits-including-energy-tax-credit-details Note 5 - Investments in Affordable Housing and Alternative Energy Partnerships - Usage of Affordable Housing and Other Tax Credits Including Energy Tax Credit (Details) Details 76 false false R77.htm 995620 - Disclosure - Note 6 - Premises and Equipment (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-6-premises-and-equipment-details-textual Note 6 - Premises and Equipment (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-6-premises-and-equipment-tables 77 false false R78.htm 995621 - Disclosure - Note 6 - Premises and Equipment - Premises and Equipment (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-6-premises-and-equipment-premises-and-equipment-details Note 6 - Premises and Equipment - Premises and Equipment (Details) Details 78 false false R79.htm 995622 - Disclosure - Note 7 - Goodwill and Other Intangible Assets (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-7-goodwill-and-other-intangible-assets-details-textual Note 7 - Goodwill and Other Intangible Assets (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-7-goodwill-and-other-intangible-assets-tables 79 false false R80.htm 995623 - Disclosure - Note 7 - Goodwill and Other Intangible Assets - Schedule of Intangible Assets (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-7-goodwill-and-other-intangible-assets-schedule-of-intangible-assets-details Note 7 - Goodwill and Other Intangible Assets - Schedule of Intangible Assets (Details) Details 80 false false R81.htm 995624 - Disclosure - Note 7 - Goodwill and Other Intangible Assets - Maturity Schedule of Intangible Assets (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-7-goodwill-and-other-intangible-assets-maturity-schedule-of-intangible-assets-details Note 7 - Goodwill and Other Intangible Assets - Maturity Schedule of Intangible Assets (Details) Details 81 false false R82.htm 995625 - Disclosure - Note 8 - Deposits (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits-details-textual Note 8 - Deposits (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits-tables 82 false false R83.htm 995626 - Disclosure - Note 8 - Deposits - Deposit Balances (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits-deposit-balances-details Note 8 - Deposits - Deposit Balances (Details) Details 83 false false R84.htm 995627 - Disclosure - Note 8 - Deposits - Time Deposit Maturities (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits-time-deposit-maturities-details Note 8 - Deposits - Time Deposit Maturities (Details) Details 84 false false R85.htm 995628 - Disclosure - Note 8 - Deposits - Interest Expense on Time Deposits (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-8-deposits-interest-expense-on-time-deposits-details Note 8 - Deposits - Interest Expense on Time Deposits (Details) Details 85 false false R86.htm 995629 - Disclosure - Note 9 - Borrowed Funds (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-9-borrowed-funds-details-textual Note 9 - Borrowed Funds (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-9-borrowed-funds 86 false false R87.htm 995630 - Disclosure - Note 10 - Capital Resources (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-10-capital-resources-details-textual Note 10 - Capital Resources (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-10-capital-resources-tables 87 false false R88.htm 995631 - Disclosure - Note 10 - Capital Resources - Outstanding Junior Subordinated Notes (Details) Notes http://www.cathaygeneralbancorp.com/20251231/role/statement-note-10-capital-resources-outstanding-junior-subordinated-notes-details Note 10 - Capital Resources - Outstanding Junior Subordinated Notes (Details) Details 88 false false R89.htm 995632 - Disclosure - Note 11 - Income Taxes (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes-details-textual Note 11 - Income Taxes (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes-tables 89 false false R90.htm 995633 - Disclosure - Note 11 - Income Taxes - Components of Income Tax Expense (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes-components-of-income-tax-expense-details Note 11 - Income Taxes - Components of Income Tax Expense (Details) Details 90 false false R91.htm 995634 - Disclosure - Note 11 - Income Taxes - Deferred Tax Assets and Liabilities (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes-deferred-tax-assets-and-liabilities-details Note 11 - Income Taxes - Deferred Tax Assets and Liabilities (Details) Details 91 false false R92.htm 995635 - Disclosure - Note 11 - Income Taxes - Income Tax Reconciliation (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes-income-tax-reconciliation-details Note 11 - Income Taxes - Income Tax Reconciliation (Details) Details 92 false false R93.htm 995636 - Disclosure - Note 11 - Income Taxes - Income Tax Paid Net of Refunds (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-11-income-taxes-income-tax-paid-net-of-refunds-details Note 11 - Income Taxes - Income Tax Paid Net of Refunds (Details) Details 93 false false R94.htm 995637 - Disclosure - Note 12 - Stockholders' Equity and Earnings Per Share (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-12-stockholders-equity-and-earnings-per-share-details-textual Note 12 - Stockholders' Equity and Earnings Per Share (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-12-stockholders-equity-and-earnings-per-share-tables 94 false false R95.htm 995638 - Disclosure - Note 12 - Stockholders' Equity and Earnings Per Share - Accumulated Other Comprehensive Income (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-12-stockholders-equity-and-earnings-per-share-accumulated-other-comprehensive-income-details Note 12 - Stockholders' Equity and Earnings Per Share - Accumulated Other Comprehensive Income (Details) Details 95 false false R96.htm 995639 - Disclosure - Note 12 - Stockholders' Equity and Earnings Per Share - Earnings Per Share (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-12-stockholders-equity-and-earnings-per-share-earnings-per-share-details Note 12 - Stockholders' Equity and Earnings Per Share - Earnings Per Share (Details) Details 96 false false R97.htm 995640 - Disclosure - Note 13 - Commitments and Contingencies (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-13-commitments-and-contingencies-details-textual Note 13 - Commitments and Contingencies (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-13-commitments-and-contingencies-tables 97 false false R98.htm 995641 - Disclosure - Note 13 - Commitments and Contingencies - Financial Instruments With Off-balance Sheet Risk (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-13-commitments-and-contingencies-financial-instruments-with-offbalance-sheet-risk-details Note 13 - Commitments and Contingencies - Financial Instruments With Off-balance Sheet Risk (Details) Details 98 false false R99.htm 995642 - Disclosure - Note 14 - Leases (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-14-leases-details-textual Note 14 - Leases (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-14-leases-tables 99 false false R100.htm 995643 - Disclosure - Note 14 - Leases - Operating Lease Related Assets and Liabilities (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-14-leases-operating-lease-related-assets-and-liabilities-details Note 14 - Leases - Operating Lease Related Assets and Liabilities (Details) Details 100 false false R101.htm 995644 - Disclosure - Note 14 - Leases - Lease Maturity Schedule (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-14-leases-lease-maturity-schedule-details Note 14 - Leases - Lease Maturity Schedule (Details) Details 101 false false R102.htm 995645 - Disclosure - Note 15 - Financial Derivatives (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-15-financial-derivatives-details-textual Note 15 - Financial Derivatives (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-15-financial-derivatives-tables 102 false false R103.htm 995646 - Disclosure - Note 15 - Financial Derivatives - Cash Flow Swap Hedges (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-15-financial-derivatives-cash-flow-swap-hedges-details Note 15 - Financial Derivatives - Cash Flow Swap Hedges (Details) Details 103 false false R104.htm 995647 - Disclosure - Note 15 - Financial Derivatives - Not Designated as Hedging Instruments (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-15-financial-derivatives-not-designated-as-hedging-instruments-details Note 15 - Financial Derivatives - Not Designated as Hedging Instruments (Details) Details 104 false false R105.htm 995648 - Disclosure - Note 16 - Fair Value Measurements and Fair Value of Financial Instruments (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments-details-textual Note 16 - Fair Value Measurements and Fair Value of Financial Instruments (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments-tables 105 false false R106.htm 995649 - Disclosure - Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments-assets-and-liabilities-measured-at-fair-value-on-a-recurring-basis-details Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) Details 106 false false R107.htm 995650 - Disclosure - Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Financial Assets Measured on a Non-recurring Basis (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments-financial-assets-measured-on-a-nonrecurring-basis-details Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Financial Assets Measured on a Non-recurring Basis (Details) Details 107 false false R108.htm 995651 - Disclosure - Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments-fair-value-of-financial-instruments-details Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) Details 108 false false R109.htm 995652 - Disclosure - Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-16-fair-value-measurements-and-fair-value-of-financial-instruments-fair-value-hierarchy-of-financial-instruments-details Note 16 - Fair Value Measurements and Fair Value of Financial Instruments - Fair Value Hierarchy of Financial Instruments (Details) Details 109 false false R110.htm 995653 - Disclosure - Note 17 - Revenue From Contracts With Clients - Summary of Revenue (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-17-revenue-from-contracts-with-clients-summary-of-revenue-details Note 17 - Revenue From Contracts With Clients - Summary of Revenue (Details) Details 110 false false R111.htm 995654 - Disclosure - Note 18 - Employee Benefit Plans (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-18-employee-benefit-plans-details-textual Note 18 - Employee Benefit Plans (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-18-employee-benefit-plans 111 false false R112.htm 995655 - Disclosure - Note 19 - Equity Incentive Plans (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-19-equity-incentive-plans-details-textual Note 19 - Equity Incentive Plans (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-19-equity-incentive-plans-tables 112 false false R113.htm 995656 - Disclosure - Note 19 - Equity Incentive Plans - Restricted Stock Units (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-19-equity-incentive-plans-restricted-stock-units-details Note 19 - Equity Incentive Plans - Restricted Stock Units (Details) Details 113 false false R114.htm 995657 - Disclosure - Note 20 - Condensed Financial Information of Cathay General Bancorp - Balance Sheets (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-20-condensed-financial-information-of-cathay-general-bancorp-balance-sheets-details Note 20 - Condensed Financial Information of Cathay General Bancorp - Balance Sheets (Details) Details 114 false false R115.htm 995658 - Disclosure - Note 20 - Condensed Financial Information of Cathay General Bancorp - Balance Sheets (Details) (Parentheticals) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-20-condensed-financial-information-of-cathay-general-bancorp-balance-sheets-details-parentheticals Note 20 - Condensed Financial Information of Cathay General Bancorp - Balance Sheets (Details) (Parentheticals) Details 115 false false R116.htm 995659 - Disclosure - Note 20 - Condensed Financial Information of Cathay General Bancorp - Statements of Operations (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-20-condensed-financial-information-of-cathay-general-bancorp-statements-of-operations-details Note 20 - Condensed Financial Information of Cathay General Bancorp - Statements of Operations (Details) Details 116 false false R117.htm 995660 - Disclosure - Note 20 - Condensed Financial Information of Cathay General Bancorp - Statements of Cash Flows (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-20-condensed-financial-information-of-cathay-general-bancorp-statements-of-cash-flows-details Note 20 - Condensed Financial Information of Cathay General Bancorp - Statements of Cash Flows (Details) Details 117 false false R118.htm 995661 - Disclosure - Note 21 - Dividend Reinvestment Plan (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-21-dividend-reinvestment-plan-details-textual Note 21 - Dividend Reinvestment Plan (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-21-dividend-reinvestment-plan 118 false false R119.htm 995662 - Disclosure - Note 22 - Regulatory Matters (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-22-regulatory-matters-details-textual Note 22 - Regulatory Matters (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-22-regulatory-matters-tables 119 false false R120.htm 995663 - Disclosure - Note 22 - Regulatory Matters - Capital and Leverage Ratios (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-22-regulatory-matters-capital-and-leverage-ratios-details Note 22 - Regulatory Matters - Capital and Leverage Ratios (Details) Details 120 false false R121.htm 995664 - Disclosure - Note 23 - Balance Sheet Offsetting - Financial Instruments That Are Eligible for Offset in the Consolidated Balance Sheet (Details) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-23-balance-sheet-offsetting-financial-instruments-that-are-eligible-for-offset-in-the-consolidated-balance-sheet-details Note 23 - Balance Sheet Offsetting - Financial Instruments That Are Eligible for Offset in the Consolidated Balance Sheet (Details) Details 121 false false R122.htm 995665 - Disclosure - Note 24 - Subsequent Events (Details Textual) Sheet http://www.cathaygeneralbancorp.com/20251231/role/statement-note-24-subsequent-events-details-textual Note 24 - Subsequent Events (Details Textual) Details http://www.cathaygeneralbancorp.com/20251231/role/statement-note-24-subsequent-events 122 false false All Reports Book All Reports caty-20251231.xsd caty-20251231_cal.xml caty-20251231_def.xml caty-20251231_lab.xml caty-20251231_pre.xml caty20251231c_10k.htm graph01.jpg http://fasb.org/srt/2025 http://fasb.org/us-gaap/2025 http://xbrl.sec.gov/cyd/2025 http://xbrl.sec.gov/dei/2025 http://xbrl.sec.gov/ecd/2025 true true