Note 11 - Capital Resources (Details) - Outstanding Junior Subordinated Notes - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	May. 31, 2014
Subordinated Borrowing [Line Items]
Principal balance of notes	$ 119,136	$ 119,100
Cathay Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Issuance date	Jun. 26, 2003
Principal balance of notes	$ 20,619
Not redeemable until	Jun. 30, 2008
Stated maturity	Jun. 30, 2033
Annualized coupon rate	3-month LIBOR + 3.15%
Current interest rate	3.75%
Date of rate change	Dec. 30, 2015
Payable/distribution date	March 30 June 30 September 30 December 30
Cathay Statutory Trust I [Member]
Subordinated Borrowing [Line Items]
Issuance date	Sep. 17, 2003
Principal balance of notes	$ 20,619
Not redeemable until	Sep. 17, 2008
Stated maturity	Sep. 17, 2033
Annualized coupon rate	3-month LIBOR + 3.00%
Current interest rate	3.53%
Date of rate change	Dec. 17, 2015
Payable/distribution date	March 17 June 17 September 17 December 17
Cathay Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Issuance date	Dec. 30, 2003
Principal balance of notes	$ 12,887
Not redeemable until	Mar. 30, 2009
Stated maturity	Mar. 30, 2034
Annualized coupon rate	3-month LIBOR + 2.90%
Current interest rate	3.50%
Date of rate change	Dec. 30, 2015
Payable/distribution date	March 30 June 30 September 30 December 30
Cathay Capital Trust III [Member]
Subordinated Borrowing [Line Items]
Issuance date	Mar. 28, 2007
Principal balance of notes	$ 46,392
Not redeemable until	Jun. 15, 2012
Stated maturity	Jun. 15, 2037
Annualized coupon rate	3-month LIBOR + 1.48%
Current interest rate	1.99%
Date of rate change	Dec. 15, 2015
Payable/distribution date	March 15 June 15 September 15 December 15
Cathay Capital Trust IV [Member]
Subordinated Borrowing [Line Items]
Issuance date	May 31, 2007
Principal balance of notes	$ 18,619
Not redeemable until	Sep. 06, 2012
Stated maturity	Sep. 06, 2037
Annualized coupon rate	3-month LIBOR + 1.4%
Current interest rate	1.85%
Date of rate change	Dec. 07, 2015
Payable/distribution date	March 6 June 6 September 6 December 6