Note 4 - Loans and Allowance for Loan Losses (Detail) - Past Due Loans (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Consumer:
Total Loans	$ 1,728,925	$ 1,737,844
Credit Cards [Member]
Consumer:
Gross 30-89 Days Past Due	614	820
90 Days or More Past Due	530	605
Total Past Due	1,144	1,425
Current	175,181	188,545
Total Loans	176,325	189,970
90 Days Past Due & Accruing	212	300
Student Loans [Member]
Consumer:
Gross 30-89 Days Past Due	1,187	1,894
90 Days or More Past Due	3,279	2,483
Total Past Due	4,466	4,377
Current	35,357	43,042
Total Loans	39,823	47,419
90 Days Past Due & Accruing	3,275	2,483
Other Consumer [Member]
Consumer:
Gross 30-89 Days Past Due	999	1,398
90 Days or More Past Due	553	664
Total Past Due	1,552	2,062
Current	105,732	107,149
Total Loans	107,284	109,211
90 Days Past Due & Accruing	181	335
Consumer Loans [Member]
Consumer:
Gross 30-89 Days Past Due	2,800	4,112
90 Days or More Past Due	4,362	3,752
Total Past Due	7,162	7,864
Current	316,270	338,736
Total Loans	323,432	346,600
90 Days Past Due & Accruing	3,668	3,118
Construction Loans [Member]
Consumer:
Gross 30-89 Days Past Due	357	548
90 Days or More Past Due	412	121
Total Past Due	769	669
Current	116,466	109,156
Total Loans	117,235	109,825
Single Family Residential Loans [Member]
Consumer:
Gross 30-89 Days Past Due	2,444	3,581
90 Days or More Past Due	1,705	2,262
Total Past Due	4,149	5,843
Current	351,829	349,251
Total Loans	355,978	355,094
90 Days Past Due & Accruing	106	121
Other Commercial Real Estate Loans [Member]
Consumer:
Gross 30-89 Days Past Due	753	806
90 Days or More Past Due	3,194	6,240
Total Past Due	3,947	7,046
Current	546,471	529,326
Total Loans	550,418	536,372
90 Days Past Due & Accruing		15
Real Estate Loans [Member]
Consumer:
Gross 30-89 Days Past Due	3,554	4,935
90 Days or More Past Due	5,311	8,623
Total Past Due	8,865	13,558
Current	1,014,766	987,733
Total Loans	1,023,631	1,001,291
90 Days Past Due & Accruing	106	136
Other Commercial Loans [Member]
Consumer:
Gross 30-89 Days Past Due	525	467
90 Days or More Past Due	247	467
Total Past Due	772	934
Current	140,096	140,488
Total Loans	140,868	141,422
90 Days Past Due & Accruing	10	9
Agricultural Loans [Member]
Consumer:
Gross 30-89 Days Past Due	369	103
90 Days or More Past Due	190	312
Total Past Due	559	415
Current	121,686	85,313
Total Loans	122,245	85,728
90 Days Past Due & Accruing		5
Commercial Loans [Member]
Consumer:
Gross 30-89 Days Past Due	894	570
90 Days or More Past Due	437	779
Total Past Due	1,331	1,349
Current	261,782	225,801
Total Loans	263,113	227,150
90 Days Past Due & Accruing	10	14
Other Loans [Member]
Consumer:
Current	4,560	4,728
Total Loans	4,560	4,728
Total Loans [Member]
Consumer:
Gross 30-89 Days Past Due	7,248
90 Days or More Past Due	10,110
Total Past Due	17,358
Current	1,597,378
Total Loans	1,614,736
90 Days Past Due & Accruing	3,784
Total Loan Portfolio [Member]
Consumer:
Gross 30-89 Days Past Due		9,617
90 Days or More Past Due		13,154
Total Past Due		22,771
Current		1,556,998
Total Loans		1,579,769
90 Days Past Due & Accruing		$ 3,268