Note 20 - Condensed Financial Information of Cathay General Bancorp (Details) - Balance Sheets (Parentheticals) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Condensed Balance Sheet Statements, Captions [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued		258,000
Preferred stock, shares outstanding		258,000
Common stock, par value (in Dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	83,797,434	82,985,853
Common stock, shares outstanding	79,589,869	78,778,288
Treasury stock, shares	4,207,565	4,207,565
Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	258,000
Preferred stock, shares outstanding	0	258,000
Common stock, par value (in Dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	83,797,434	82,985,853
Common stock, shares outstanding	79,589,869	78,778,288
Treasury stock, shares	4,207,565	4,207,565