Note 9 - Capital Resources - Outstanding Junior Subordinated Notes (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	May 31, 2014
Junior subordinated debt	$ 119,136	$ 119,100
Cathay Capital Trust I [Member]
Junior subordinated debt	$ 20,619
Annualized coupon rate	3-month
Current interest rate	5.11%
Payable/distribution date	March 30
Cathay Statutory Trust I [Member]
Junior subordinated debt	$ 20,619
Annualized coupon rate	3-month
Current interest rate	4.90%
Payable/distribution date	March 17
Cathay Capital Trust II [Member]
Junior subordinated debt	$ 12,887
Annualized coupon rate	3-month
Current interest rate	4.86%
Payable/distribution date	March 30
Cathay Capital Trust III [Member]
Junior subordinated debt	$ 46,392
Annualized coupon rate	3-month
Current interest rate	3.37%
Payable/distribution date	March 15
Cathay Capital Trust IV [Member]
Junior subordinated debt	$ 18,619
Annualized coupon rate	3-month
Current interest rate	3.29%
Payable/distribution date	March 6