Note 11 - Capital Resources (Detail) - Outstanding Junior Subordinated Notes (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Principal Balance of Notes	$ 121,136
Cathay Capital Trust I [Member]
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	3.46%
Date of Rate Change	Dec. 30, 2012
Payable/Distribution Date	March 30 June 30 September 30 December 30
Cathay Statutory Trust I [Member]
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	3.31%
Date of Rate Change	Dec. 17, 2012
Payable/Distribution Date	March 17 June 17 September 17 December 17
Cathay Capital Trust II [Member]
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	3.21%
Date of Rate Change	Dec. 30, 2012
Payable/Distribution Date	March 30 June 30 September 30 December 30
Cathay Capital Trust III [Member]
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	1.79%
Date of Rate Change	Dec. 17, 2012
Payable/Distribution Date	March 15 June 15 September 15 December 15
Cathay Capital Trust IV [Member]
Issuance Date	May 31, 2007
Principal Balance of Notes	$ 20,619
Not Redeemable Until	Sep. 06, 2012
Stated Maturity	Sep. 06, 2037
Annualized Coupon Rate	3-month LIBOR 1.40%
Current Interest Rate	1.71%
Date of Rate Change	Dec. 06, 2012
Payable/Distribution Date	March 6 June 6 September 6 December 6