Note 12 - Fair Value Measurements and Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Securities available-for-sale	$ 1,434,040	$ 1,547,128
Equity securities	30,238	34,429
Interest rate swaps	32,468	39,958
Interest rate swaps	33,565	36,319
Fair Value, Recurring [Member]
Equity securities	28,699	32,890
Assets, fair value disclosure	1,495,785	1,620,466
Liabilities, fair value disclosure	33,889	37,104
Fair Value, Recurring [Member] \| Interest Rate Swap [Member]
Interest rate swaps	32,468	39,958
Interest rate swaps	33,565	36,319
Fair Value, Recurring [Member] \| Foreign Exchange Contract [Member]
Foreign exchange contracts	578	490
Foreign exchange contracts	324	785
Fair Value, Recurring [Member] \| Mutual Funds [Member]
Equity securities	5,615	5,532
Fair Value, Recurring [Member] \| Preferred Stock of Government Sponsored Entities [Member]
Equity securities	7,245	7,287
Fair Value, Recurring [Member] \| Other Equity Securities [Member]
Equity securities	15,839	20,071
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Equity securities	28,699	32,890
Assets, fair value disclosure	570,343	654,352
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Interest Rate Swap [Member]
Interest rate swaps	0	0
Interest rate swaps	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Foreign Exchange Contract [Member]
Foreign exchange contracts	0	0
Foreign exchange contracts	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Equity securities	5,615	5,532
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Preferred Stock of Government Sponsored Entities [Member]
Equity securities	7,245	7,287
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Other Equity Securities [Member]
Equity securities	15,839	20,071
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Equity securities	0	0
Assets, fair value disclosure	925,442	966,114
Liabilities, fair value disclosure	33,889	37,104
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Interest Rate Swap [Member]
Interest rate swaps	32,468	39,958
Interest rate swaps	33,565	36,319
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Foreign Exchange Contract [Member]
Foreign exchange contracts	578	490
Foreign exchange contracts	324	785
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Equity securities	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Preferred Stock of Government Sponsored Entities [Member]
Equity securities	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Other Equity Securities [Member]
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Equity securities	0	0
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Interest Rate Swap [Member]
Interest rate swaps	0	0
Interest rate swaps	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Foreign Exchange Contract [Member]
Foreign exchange contracts	0	0
Foreign exchange contracts	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Mutual Funds [Member]
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Preferred Stock of Government Sponsored Entities [Member]
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Other Equity Securities [Member]
Equity securities	0	0
US Treasury Securities [Member]
Securities available-for-sale	541,644	621,462
US Treasury Securities [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	541,644	621,462
US Treasury Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	541,644	621,462
US Treasury Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
US Treasury Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	8,723	9,149
US Government Corporations and Agencies Securities [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	8,723	9,149
US Government Corporations and Agencies Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
US Government Corporations and Agencies Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	8,723	9,149
US Government Corporations and Agencies Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
Commercial Mortgage-Backed Securities [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	679,675	684,016
Commercial Mortgage-Backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
Commercial Mortgage-Backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	679,675	684,016
Commercial Mortgage-Backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
Collateralized Mortgage Obligations [Member]
Securities available-for-sale	24,663	24,556
Collateralized Mortgage Obligations [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	24,663	24,556
Collateralized Mortgage Obligations [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
Collateralized Mortgage Obligations [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	24,663	24,556
Collateralized Mortgage Obligations [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
Corporate Debt Securities [Member]
Securities available-for-sale	179,335	207,945
Corporate Debt Securities [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	179,335	207,945
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	0	0
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	179,335	207,945
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Securities available-for-sale	$ 0	$ 0

CATHAY GENERAL BANCORP 10-Q