Regulatory Requirements and Matters (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Capital adequacy
Minimum common equity tier 1 capital adequacy to risk weighted assets	4.50%
Tier 1 risk based capital ratio required for capital adequacy to risk weighted assets	0.060
Tier 1 leverage capital (to adjusted average assets), Ratio (as a percent)	0.040
Total capital ratio required for capital adequacy to risk weighted assets	0.080
Fully phased-in capital conservation buffer	2.50%	2.50%
East West Bank
Capital adequacy
Daily average reserve requirement	$ 0.0	$ 829.0