Note 20 - Condensed Financial Information of Cathay General Bancorp (Details) - Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets
Cash	$ 153,747,000	$ 144,909,000	$ 117,888,000	$ 87,347,000
Other assets	190,634,000	166,595,000
Total assets	10,989,286,000	10,694,089,000
Liabilities
Junior subordinated debt	121,136
Other liabilities	55,418,000	54,040,000
Total liabilities	9,530,315,000	9,064,585,000
Stockholders' equity
Preferred stock, 10,000,000 shares authorized, none issued and outstanding at December 31, 2013, 258,000 issued and outstanding at December 31, 2012		254,580,000
Common stock, $0.01 par value, 100,000,000 shares authorized, 83,797,434 issued and 79,589,869 outstanding at December 31, 2013, and 82,985,853 issued and 78,778,288 outstanding at December 31, 2012	838,000	830,000
Additional paid-in-capital	784,489,000	768,925,000
Accumulated other comprehensive loss, net	(29,729,000)	465,000
Retained earnings	829,109,000	721,993,000
Treasury stock, at cost (4,207,565 shares at December 31, 2013, and at December 31, 2012)	125,736,000	125,736,000
Total stockholders' equity	1,458,971,000	1,621,057,000
Total liabilities and stockholders' equity	10,989,286,000	10,694,089,000
Bank Subsidiaries [Member] | Parent Company [Member]
Assets
Investment in subsidiaries	1,525,459,000	1,569,902,000
Non-Bank Subsidiaries [Member] | Parent Company [Member]
Assets
Investment in subsidiaries	2,536,000	2,598,000
Parent Company [Member]
Assets
Cash	1,835,000	639,000
Short-term certificates of deposit	38,000,000	161,300,000
Other assets	12,866,000	9,936,000
Total assets	1,580,696,000	1,744,375,000
Liabilities
Junior subordinated debt	121,136,000	121,136,000
Other liabilities	589,000	2,182,000
Total liabilities	121,725,000	123,318,000
Stockholders' equity
Preferred stock, 10,000,000 shares authorized, none issued and outstanding at December 31, 2013, 258,000 issued and outstanding at December 31, 2012		254,580,000
Common stock, $0.01 par value, 100,000,000 shares authorized, 83,797,434 issued and 79,589,869 outstanding at December 31, 2013, and 82,985,853 issued and 78,778,288 outstanding at December 31, 2012	838,000	830,000
Additional paid-in-capital	784,489,000	768,925,000
Accumulated other comprehensive loss, net	(29,729,000)	465,000
Retained earnings	829,109,000	721,993,000
Treasury stock, at cost (4,207,565 shares at December 31, 2013, and at December 31, 2012)	(125,736,000)	(125,736,000)
Total stockholders' equity	1,458,971,000	1,621,057,000
Total liabilities and stockholders' equity	$ 1,580,696,000	$ 1,744,375,000