Note 20 - Condensed Financial Information of Cathay General Bancorp (Details) - Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from Operating Activities
Net income	$ 123,143	$ 117,438	$ 100,150
Write-downs on venture capital and other investments	409	309	379
Write-downs on impaired securities		181	200
Excess tax short-fall from stock options	2,509	620	290
Net change in other assets	23,525	43,304	2,622
Net change in other liabilities	(4,973)	(2,256)	3,746
Net cash provided by/(used in) operating activities	115,073	164,576	174,050
Cash flows from Investment Activities
Proceeds from sale of available-for-sale securities	(350,130)	(517,513)	(571,093)
Net cash provided by/(used in) investment activities	(311,806)	(46,536)	127,050
Cash flows from Financing Activities
Cash dividends	(12,606)	(16,049)	(16,046)
Proceeds from exercise of stock options	14,755	764	1,306
Excess tax short-fall from share-based payment arrangements	(2,509)	(620)	(290)
Net cash used in financing activities	205,571	(91,019)	(270,559)
Increase/(decrease) in cash and cash equivalents	8,838	27,021	30,541
Cash and cash equivalents,	153,747	144,909	117,888
Series B Preferred Stock [Member] | Parent Company [Member]
Cash flows from Financing Activities
Redemption of Series B preferred stock	(258,000)
Series B Preferred Stock [Member]
Cash flows from Financing Activities
Redemption of Series B preferred stock	(258,000)
Parent Company [Member]
Cash flows from Operating Activities
Net income	123,143	117,438	100,150
Dividends in excess of earnings of subsidiaries	12,078	36,463
Equity in undistributed earnings of subsidiaries	12,078	36,463	(102,492)
Gains on sale of securities		(3,380)
Increase in accrued expense		12	24
Write-downs on venture capital and other investments	357	262	321
Write-downs on impaired securities		181	200
Loss/(gains) in fair value of warrants	56	114	(215)
Excess tax short-fall from stock options	2,509	620	290
Net change in other assets	(1,684)	1,820	(121)
Net change in other liabilities	27	59	(221)
Net cash provided by/(used in) operating activities	136,486	153,589	(2,064)
Cash flows from Investment Activities
Decrease/(increase) in short-term investment	123,300	(142,300)	17,500
Proceeds from sale of available-for-sale securities		4,849
Venture capital and other investments	(835)	(694)	(671)
Net cash provided by/(used in) investment activities	122,465	(138,145)	16,829
Cash flows from Financing Activities
Cash dividends	(12,606)	(16,049)	(16,046)
Proceeds from shares issued under the Dividend Reinvestment Plan	605	291	287
Proceeds from exercise of stock options	14,755	764	1,306
Excess tax short-fall from share-based payment arrangements	(2,509)	(620)	(290)
Net cash used in financing activities	(257,755)	(15,614)	(14,743)
Increase/(decrease) in cash and cash equivalents	1,196	(170)	22
Cash and cash equivalents,	1,835	639
Parent Company [Member] | Beginning of Period [Member]
Cash flows from Financing Activities
Cash and cash equivalents,	639	809	787
Parent Company [Member] | End of Period [Member]
Cash flows from Financing Activities
Cash and cash equivalents,	$ 1,835	$ 639	$ 809