Note 4 - Loans and Allowance for Loan Losses (Detail) - Age analysis of past due loans, excluding loans acquired, segregated by class of loans: (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Total Loans	$ 1,628,513	$ 1,579,769
Consumer Loans [Member] | Credit Cards [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	710	820
90 Days or More Past Due	547	605
Total Past Due	1,257	1,425
Current	184,279	188,545
Total Loans	185,536	189,970
90 Days Past Due & Accruing	266	300
Consumer Loans [Member] | Credit Cards [Member]
Total Loans	185,536	189,970
Consumer Loans [Member] | Student Loans [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	901	1,894
90 Days or More Past Due	2,234	2,483
Total Past Due	3,135	4,377
Current	31,010	43,042
Total Loans	34,145	47,419
90 Days Past Due & Accruing	2,234	2,483
Consumer Loans [Member] | Student Loans [Member]
Total Loans	34,145	47,419
Consumer Loans [Member] | Other Consumer [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	1,149	1,398
90 Days or More Past Due	529	664
Total Past Due	1,678	2,062
Current	103,641	107,149
Total Loans	105,319	109,211
90 Days Past Due & Accruing	204	335
Consumer Loans [Member] | Other Consumer [Member]
Total Loans	105,319	109,211
Consumer Loans [Member] | Total Consumer [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	2,760	4,112
90 Days or More Past Due	3,310	3,752
Total Past Due	6,070	7,864
Current	318,930	338,736
Total Loans	325,000	346,600
90 Days Past Due & Accruing	2,704	3,118
Consumer Loans [Member] | Total Consumer [Member]
Total Loans	325,000	346,600
Real Estate Loans [Member] | Construction Loans [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	309	548
90 Days or More Past Due	365	121
Total Past Due	674	669
Current	137,458	109,156
Total Loans	138,132	109,825
Real Estate Loans [Member] | Construction Loans [Member]
Total Loans	138,132	109,825
Real Estate Loans [Member] | Single Family Residential Loans [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	3,069	3,581
90 Days or More Past Due	1,539	2,262
Total Past Due	4,608	5,843
Current	352,299	349,251
Total Loans	356,907	355,094
90 Days Past Due & Accruing	137	121
Real Estate Loans [Member] | Single Family Residential Loans [Member]
Total Loans	356,907	355,094
Real Estate Loans [Member] | Other Commercial Real Estate Loans [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	716	806
90 Days or More Past Due	3,303	6,240
Total Past Due	4,019	7,046
Current	564,147	529,326
Total Loans	568,166	536,372
90 Days Past Due & Accruing		15
Real Estate Loans [Member] | Other Commercial Real Estate Loans [Member]
Total Loans	568,166	536,372
Real Estate Loans [Member] | Total Real Estate [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	4,094	4,935
90 Days or More Past Due	5,207	8,623
Total Past Due	9,301	13,558
Current	1,053,904	987,733
Total Loans	1,063,205	1,001,291
90 Days Past Due & Accruing	137	136
Real Estate Loans [Member] | Total Real Estate [Member]
Total Loans	1,063,205	1,001,291
Commercial Loans [Member] | Commercial [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	340	467
90 Days or More Past Due	385	467
Total Past Due	725	934
Current	140,611	140,488
Total Loans	141,336	141,422
90 Days Past Due & Accruing	74	9
Commercial Loans [Member] | Commercial [Member]
Total Loans	141,336	141,422
Commercial Loans [Member] | Agricultural Loans [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	81	103
90 Days or More Past Due	113	312
Total Past Due	194	415
Current	93,611	85,313
Total Loans	93,805	85,728
90 Days Past Due & Accruing		5
Commercial Loans [Member] | Agricultural Loans [Member]
Total Loans	93,805	85,728
Commercial Loans [Member] | Total Commercial [Member] | Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	421	570
90 Days or More Past Due	498	779
Total Past Due	919	1,349
Current	234,222	225,801
Total Loans	235,141	227,150
90 Days Past Due & Accruing	74	14
Commercial Loans [Member] | Total Commercial [Member]
Total Loans	235,141	227,150
Credit Cards [Member] | Loans, excluding acquired loans [Member]
Total Loans	185,536	189,970
Other Loans [Member] | Loans, excluding acquired loans [Member]
Current	5,167	4,728
Total Loans	5,167	4,728
Other Loans [Member]
Total Loans	5,167	4,728
Loans, excluding acquired loans [Member]
Gross 30-89 Days Past Due	7,275	9,617
90 Days or More Past Due	9,015	13,154
Total Past Due	16,290	22,771
Current	1,612,223	1,556,998
Total Loans	1,628,513	1,579,769
90 Days Past Due & Accruing	$ 2,915	$ 3,268