Condensd Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Interest and Dividend Income
Loans receivable, including loan fees	$ 90,838	$ 90,024	$ 267,557	$ 269,486
Investment securities- taxable	10,868	15,157	34,986	50,046
Investment securities- nontaxable		1,036	995	3,127
Federal Home Loan Bank stock	449	57	1,041	190
Federal funds sold and securities purchased under agreements to resell		2		18
Deposits with banks	307	471	796	1,596
Total interest and dividend income	102,462	106,747	305,375	324,463
Interest Expense
Time deposits of $100,000 or more	6,887	7,970	20,466	26,152
Other deposits	3,485	3,261	9,244	11,045
Securities sold under agreements to repurchase	8,402	13,734	29,778	42,987
Advances from Federal Home Loan Bank	150	74	375	196
Long-term debt	930	1,291	2,778	3,895
Total interest expense	19,854	26,330	62,641	84,275
Net interest income before provision for credit losses	82,608	80,417	242,734	240,188
Provision/(credit) for loan losses	(3,000)		(3,000)	(9,000)
Net interest income after provision/(credit) for loan losses	85,608	80,417	245,734	249,188
Non-Interest Income
Securities gains, net	8,688	8,652	27,157	13,241
Letters of credit commissions	1,698	1,728	4,608	4,873
Depository service fees	1,371	1,342	4,330	4,114
Other operating income	4,963	3,900	15,867	12,077
Total non-interest income	16,720	15,622	51,962	34,305
Non-interest Expense
Salaries and employee benefits	22,751	18,451	67,192	58,426
Occupancy expense	3,812	3,853	10,966	10,926
Computer and equipment expense	2,446	2,340	7,488	7,194
Professional services expense	5,813	5,273	18,484	15,224
FDIC and State assessments	1,712	2,094	5,431	6,554
Marketing expense	1,097	519	2,703	3,408
Other real estate owned expense	527	1,794	886	13,548
Operations of affordable housing investments, net	1,234	476	4,952	4,387
Amortization of core deposit intangibles	1,363	1,404	4,097	4,265
Costs associated with debt redemption	6,861	3,450	22,557	6,200
Other operating expense	3,054	8,190	8,758	12,925
Total non-interest expense	50,670	47,844	153,514	143,057
Income before income tax expense	51,658	48,195	144,182	140,436
Income tax expense	19,029	17,686	52,489	50,852
Net income	32,629	30,509	91,693	89,584
Less: net income attributable to noncontrolling interest	151	151	452	452
Net income attributable to Cathay General Bancorp	32,478	30,358	91,241	89,132
Dividends on preferred stock and noncash charge from repayment	(2,434)	(4,123)	(9,685)	(12,361)
Net income attributable to common stockholders	30,044	26,235	81,556	76,771
Other comprehensive (loss)/income, net of tax
Unrealized holding (loss)/gain arising during the period	(1,074)	10,650	(5,908)	18,353
Less: reclassification adjustments included in net income	5,036	5,015	15,740	7,674
Total other comprehensive (loss)/gain, net of tax	(6,110)	5,635	(21,648)	10,679
Total comprehensive income	$ 26,368	$ 35,993	$ 69,593	$ 99,811
Net income per common share:
Basic (in Dollars per share)	$ 0.38	$ 0.33	$ 1.03	$ 0.98
Diluted (in Dollars per share)	$ 0.38	$ 0.33	$ 1.03	$ 0.98
Cash dividends paid per common share (in Dollars per share)	$ 0.01	$ 0.01	$ 0.03	$ 0.03
Average common shares outstanding
Basic (in Shares)	78,894,262	78,729,272	78,853,333	78,706,150
Diluted (in Shares)	79,114,122	78,731,180	78,944,152	78,711,235