PARENT COMPANY FINANCIAL STATEMENTS (Details) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ASSETS
Cash and cash equivalents	$ 1,323,106	$ 1,431,185	$ 1,333,949	$ 1,099,084
Other assets	517,718	500,640
TOTAL	22,536,110	21,968,667	20,700,537
LIABILITIES AND STOCKHOLDERS' EQUITY
Long-term debt	137,178	212,178
Total liabilities	20,153,988	19,656,924
STOCKHOLDERS' EQUITY
Preferred stock, $0.001 par value, 5,000,000 shares authorized; Series A, non-cumulative convertible, 200,000 shares issued and 85,710 shares outstanding in 2012 and 2011.	83,027	83,027
Common stock, $0.001 par value, 200,000,000 shares authorized; 157,160,193 and 156,798,011 shares issued in 2012 and 2011, respectively; 140,294,092 and 149,327,907 shares outstanding in 2012 and 2011, respectively.	157	157
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	157,160,193	156,798,011
Common stock, shares outstanding	140,294,092	149,327,907
Additional paid in capital	1,464,739	1,443,883
Retained earnings	1,151,828	934,617
Treasury stock, at cost - 16,866,101 shares in 2012 and 7,470,104 shares in 2011.	(322,298)	(116,001)
Treasury stock, shares	16,866,101	7,470,104
Accumulated other comprehensive income (loss), net of tax	4,669	(33,940)	(12,414)	599
Total stockholders' equity	2,382,122	2,311,743	2,113,931	2,284,659
TOTAL	22,536,110	21,968,667
Preferred stock, Series A, non-cumulative convertible
STOCKHOLDERS' EQUITY
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	200,000	200,000
Preferred stock, shares outstanding	85,710	85,710
East West Bancorp, Inc.
ASSETS
Cash and cash equivalents	64,489	9,287	4,973	206,207
Investment in subsidiaries	2,450,058	2,436,574
Other investments	3,083	538
Other assets	5,122	3,012
TOTAL	2,522,752	2,449,411
LIABILITIES AND STOCKHOLDERS' EQUITY
Long-term debt	137,178	137,178
Other liabilities	3,452	490
Total liabilities	140,630	137,668
STOCKHOLDERS' EQUITY
Common stock, $0.001 par value, 200,000,000 shares authorized; 157,160,193 and 156,798,011 shares issued in 2012 and 2011, respectively; 140,294,092 and 149,327,907 shares outstanding in 2012 and 2011, respectively.	157	157
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	157,160,193	156,798,011
Common stock, shares outstanding	140,294,092	149,327,907
Additional paid in capital	1,464,739	1,443,883
Retained earnings	1,151,828	934,617
Treasury stock, at cost - 16,866,101 shares in 2012 and 7,470,104 shares in 2011.	(322,298)	(116,001)
Treasury stock, shares	16,866,101	7,470,104
Accumulated other comprehensive income (loss), net of tax	4,669	(33,940)
Total stockholders' equity	2,382,122	2,311,743
TOTAL	2,522,752	2,449,411
East West Bancorp, Inc. | Preferred stock, Series A, non-cumulative convertible
STOCKHOLDERS' EQUITY
Preferred stock, $0.001 par value, 5,000,000 shares authorized; Series A, non-cumulative convertible, 200,000 shares issued and 85,710 shares outstanding in 2012 and 2011.	$ 83,027	$ 83,027
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	200,000	200,000
Preferred stock, shares outstanding	85,710	85,710