Note 4 - Loans and Allowance for Credit Losses (Detail) - Impaired loans (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Commercial [Member]
Impaired loans with no related allowance recorded, Recorded Investment	$ 3,100	$ 5,483
Impaired loans with no related allowance recorded, Unpaid Principal Balance	9,506	11,727
Impaired loans with an allowance recorded, Recorded Investment	12,129
Impaired loans with an allowance recorded, Unpaid Principal Balance	13,739
Impaired loans with an allowance recorded, Related Allowance	2,588
Total Impaired loans, Recorded Investment	15,229	5,483
Total Impaired loans, Unpaid Principal Balance	23,245	11,727
Total Impaired loans, Related Allowance	2,588
Commercial Real Estate Loans [Member]
Impaired loans with no related allowance recorded, Recorded Investment	24,135	33,095
Impaired loans with no related allowance recorded, Unpaid Principal Balance	27,972	43,793
Impaired loans with an allowance recorded, Recorded Investment	4,038	1,399
Impaired loans with an allowance recorded, Unpaid Principal Balance	4,038	1,399
Impaired loans with an allowance recorded, Related Allowance	164	229
Total Impaired loans, Recorded Investment	28,173	34,494
Total Impaired loans, Unpaid Principal Balance	32,010	45,192
Total Impaired loans, Related Allowance	164	229
Construction [Member]
Impaired loans with no related allowance recorded, Recorded Investment	2,363	4,194
Impaired loans with no related allowance recorded, Unpaid Principal Balance	2,992	7,209
Impaired loans with an allowance recorded, Recorded Investment		3,126
Impaired loans with an allowance recorded, Unpaid Principal Balance		3,183
Impaired loans with an allowance recorded, Related Allowance		1,794
Total Impaired loans, Recorded Investment	2,363	7,320
Total Impaired loans, Unpaid Principal Balance	2,992	10,392
Total Impaired loans, Related Allowance		1,794
Residential Real Estate Loans [Member]
Impaired loans with no related allowance recorded, Recorded Investment	668
Impaired loans with no related allowance recorded, Unpaid Principal Balance	668
Total Impaired loans, Recorded Investment	668
Total Impaired loans, Unpaid Principal Balance	668
Consumer Installment And Other [Member]
Impaired loans with no related allowance recorded, Recorded Investment	2,328	2,990
Impaired loans with no related allowance recorded, Unpaid Principal Balance	2,616	3,658
Total Impaired loans, Recorded Investment	2,328	2,990
Total Impaired loans, Unpaid Principal Balance	$ 2,616	$ 3,658