Note 11 - Capital Resources - Outstanding Junior Subordinated Notes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	May 31, 2014
Junior subordinated debt	$ 119,136	$ 119,136	$ 119,100
Cathay Capital Trust I [Member]
Junior subordinated debt	$ 20,619	$ 20,619
current interest rate	6.82%	3.37%
coupon rate	3.15%	3.15%
Cathay Statutory Trust I [Member]
Junior subordinated debt	$ 20,619	$ 20,619
current interest rate	6.53%	3.22%
coupon rate	3.00%	3.00%
Cathay Capital Trust II [Member]
Junior subordinated debt	$ 12,887	$ 12,887
current interest rate	6.57%	3.12%
coupon rate	2.90%	2.90%
Cathay Capital Trust III [Member]
Junior subordinated debt	$ 46,392	$ 46,392
current interest rate	4.77%	1.68%
coupon rate	1.48%	1.48%
Cathay Capital Trust IV [Member]
Junior subordinated debt	$ 18,619	$ 18,619
current interest rate	4.54%	1.58%
coupon rate	1.40%	1.40%