Condensed Consolidated Statements of Operations and Comprehensive Income (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
INTEREST AND DIVIDEND INCOME
Loans receivable, including loan fees	$ 90,701	$ 90,558
Investment securities- taxable	17,723	21,854
Investment securities- nontaxable	1,052	1,056
Federal Home Loan Bank stock	66	47
Federal funds sold and securities purchased under agreements to resell	5	41
Deposits with banks	588	221
Total interest and dividend income	110,135	113,777
INTEREST EXPENSE
Time deposits of $100,000 or more	9,540	10,725
Other deposits	3,916	5,720
Securities sold under agreements to repurchase	14,655	16,171
Advances from Federal Home Loan Bank	53	4,849
Long-term debt	1,320	1,206
Short-term borrowings		1
Total interest expense	29,484	38,672
Net interest income before provision for credit losses	80,651	75,105
Provision (credit) for loan losses	(4,000)	6,000
Net interest income after provision for loan losses	84,651	69,105
NON-INTEREST INCOME
Securities gains, net	2,215	6,232
Letters of credit commissions	1,526	1,278
Depository service fees	1,389	1,361
Other operating income	3,701	3,755
Total non-interest income	8,831	12,626
NON-INTEREST EXPENSE
Salaries and employee benefits	19,878	18,271
Occupancy expense	3,584	3,538
Computer and equipment expense	2,463	2,183
Professional services expense	4,742	3,729
FDIC and State assessments	2,489	4,317
Marketing expense	1,406	695
Other real estate owned expense	4,693	221
Operations of affordable housing investments, net	1,960	1,976
Amortization of core deposit intangibles	1,457	1,481
Cost associated with debt redemption	2,750	8,811
Other operating expense	2,449	2,561
Total non-interest expense	47,871	47,783
Income before income tax expense	45,611	33,948
Income tax expense	16,547	11,734
Net income	29,064	22,214
Less: net income attributable to noncontrolling interest	151	151
Net income attributable to Cathay General Bancorp	28,913	22,063
Dividends on preferred stock	(4,117)	(4,105)
Net income attributable to common stockholders	24,796	17,958
Other comprehensive income/(loss), net of tax
Unrealized holding gain/(loss) arising during the period	5,479	(950)
Less: reclassification adjustments included in net income	1,284	2,620
Total other comprehensive gain/(loss), net of tax	4,195	(3,570)
Total comprehensive income	$ 33,108	$ 18,493
Net income per common share:
Basic (in Dollars per share)	$ 0.32	$ 0.23
Diluted (in Dollars per share)	$ 0.32	$ 0.23
Cash dividends paid per common share (in Dollars per share)	$ 0.01	$ 0.01
Average common shares outstanding
Basic (in Shares)	78,678,645	78,609,460
Diluted (in Shares)	78,690,132	78,635,620