Condensd Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Interest and Dividend Income
Loans receivable, including loan fees	$ 87,879	$ 88,761	$ 176,719	$ 179,462
Investment securities- taxable	12,332	17,166	24,118	34,889
Investment securities- nontaxable	28	1,039	995	2,091
Federal Home Loan Bank stock	342	67	592	133
Federal funds sold and securities purchased under agreements to resell		11		16
Deposits with banks	281	537	489	1,125
Total interest and dividend income	100,862	107,581	202,913	217,716
Interest Expense
Time deposits of $100,000 or more	6,822	8,642	13,579	18,182
Other deposits	2,993	3,868	5,759	7,784
Securities sold under agreements to repurchase	9,984	14,598	21,376	29,253
Advances from Federal Home Loan Bank	145	69	225	122
Long-term debt	924	1,284	1,848	2,604
Total interest expense	20,868	28,461	42,787	57,945
Net interest income before provision for credit losses	79,994	79,120	160,126	159,771
Provision/(credit) for loan losses		(5,000)		(9,000)
Net interest income after provision/(credit) for loan losses	79,994	84,120	160,126	168,771
Non-Interest Income
Securities gains, net	12,177	2,374	18,469	4,589
Letters of credit commissions	1,449	1,619	2,910	3,145
Depository service fees	1,485	1,383	2,959	2,772
Other operating income	5,250	4,476	10,904	8,177
Total non-interest income	20,361	9,852	35,242	18,683
Non-interest Expense
Salaries and employee benefits	21,588	20,097	44,441	39,975
Occupancy expense	3,510	3,489	7,154	7,073
Computer and equipment expense	2,366	2,391	5,042	4,854
Professional services expense	6,854	5,209	12,671	9,951
FDIC and State assessments	1,981	1,971	3,719	4,460
Marketing expense	1,169	1,483	1,606	2,889
Other real estate owned (income)/expense	(264)	7,061	359	11,754
Operations of affordable housing investments, net	2,023	1,951	3,718	3,911
Amortization of core deposit intangibles	1,338	1,404	2,734	2,861
Costs associated with debt redemption	10,051		15,696	2,750
Other operating expense	3,100	2,286	5,704	4,735
Total non-interest expense	53,716	47,342	102,844	95,213
Income before income tax expense	46,639	46,630	92,524	92,241
Income tax expense	16,573	16,619	33,460	33,166
Net income	30,066	30,011	59,064	59,075
Less: net income attributable to noncontrolling interest	150	150	301	301
Net income attributable to Cathay General Bancorp	29,916	29,861	58,763	58,774
Dividends on preferred stock and noncash charge from repayment	(2,067)	(4,121)	(7,251)	(8,238)
Net income attributable to common stockholders	27,849	25,740	51,512	50,536
Other comprehensive (loss)/income, net of tax
Unrealized holding (loss)/gain arising during the period	(31,492)	2,225	(4,833)	7,704
Less: reclassification adjustments included in net income	7,058	1,376	10,705	2,660
Total other comprehensive (loss)/gain, net of tax	(38,550)	849	(15,538)	5,044
Total comprehensive (loss)/income	$ (8,634)	$ 30,710	$ 43,225	$ 63,818
Net income per common share:
Basic (in Dollars per share)	$ 0.35	$ 0.33	$ 0.65	$ 0.64
Diluted (in Dollars per share)	$ 0.35	$ 0.33	$ 0.65	$ 0.64
Cash dividends paid per common share (in Dollars per share)	$ 0.01	$ 0.01	$ 0.02	$ 0.02
Average common shares outstanding
Basic (in Shares)	78,869,089	78,710,279	78,832,530	78,694,462
Diluted (in Shares)	78,899,906	78,712,172	78,857,758	78,701,152