Note 8 - Loans and the Allowance for Loan Losses (Detail) - Allowance for Loan Losses by Portfolio Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Balance, beginning of year	$ 29,740	$ 30,413	$ 29,726	$ 29,726
Provision charged to expense	10,026	10,100	9,925	51,803
Less: loans charged off	17,863	19,746	20,657	51,877
Recoveries	569	1,705	135	761
Balance, end of period	22,472	22,472	19,129	30,413
Ending Balance: individually evaluated for impairment	6,892	6,892	8,825	15,216
Ending Balance: collectively evaluated for impairment	15,580	15,580	10,304	15,197
Ending Balance	520,649	520,649	657,687	621,021
Ending Balance: individually evaluated for impairment	72,555	72,555	97,606	104,290
Ending Balance: collectively evaluated for impairment	448,094	448,094	560,081	516,731
Commercial Loans [Member]
Balance, beginning of year	5,055	5,240	4,435	4,435
Provision charged to expense	268	225	(592)	4,494
Less: loans charged off	1,303	1,544	1,556	4,059
Recoveries	21	120	44	370
Balance, end of period	4,041	4,041	2,331	5,240
Ending Balance: individually evaluated for impairment	1,290	1,290	1,879	2,632
Ending Balance: collectively evaluated for impairment	2,751	2,751	452	2,608
Ending Balance	50,914	50,914	129,771	62,609
Ending Balance: individually evaluated for impairment	4,413	4,413	11,477	4,803
Ending Balance: collectively evaluated for impairment	46,501	46,501	118,294	57,806
Agricultural [Member]
Balance, beginning of year	28	55	99	99
Provision charged to expense	(12)	(39)	(26)	(35)
Less: loans charged off			16	16
Recoveries				7
Balance, end of period	16	16	57	55
Ending Balance: collectively evaluated for impairment	16	16	57	55
Ending Balance	22,392	22,392	64,354	61,251
Ending Balance: individually evaluated for impairment			1,822
Ending Balance: collectively evaluated for impairment	22,392	22,392	62,532	61,251
Agricultural Real Estate [Member]
Balance, beginning of year	284	548	107	107
Provision charged to expense	1,184	920	24	(2,675)
Less: loans charged off	911	911	22	2,242
Recoveries				8
Balance, end of period	557	557	61	548
Ending Balance: individually evaluated for impairment	173	173		229
Ending Balance: collectively evaluated for impairment	384	384	61	319
Ending Balance	53,328	53,328	49,391	60,523
Ending Balance: individually evaluated for impairment	3,545	3,545	1,078	5,530
Ending Balance: collectively evaluated for impairment	49,783	49,783	48,313	54,993
Commercial Real Estate Loans [Member]
Balance, beginning of year	10,189	11,606	6,029	6,029
Provision charged to expense	713	(60)	7,812	24,479
Less: loans charged off	1,292	1,956	8,481	18,951
Recoveries	322	342		49
Balance, end of period	9,932	9,932	5,360	11,606
Ending Balance: individually evaluated for impairment	2,004	2,004	1,169	2,337
Ending Balance: collectively evaluated for impairment	7,928	7,928	4,191	9,269
Ending Balance	230,837	230,837	201,571	235,103
Ending Balance: individually evaluated for impairment	33,590	33,590	31,919	35,042
Ending Balance: collectively evaluated for impairment	197,247	197,247	169,652	200,661
Commercial Real Estate Development [Member]
Balance, beginning of year	10,297	8,771	15,526	15,526
Provision charged to expense	6,781	7,362	1,182	14,564
Less: loans charged off	13,455	13,474	8,462	21,401
Recoveries	150	1,114		82
Balance, end of period	3,773	3,773	8,246	8,771
Ending Balance: individually evaluated for impairment	1,512	1,512	4,722	8,215
Ending Balance: collectively evaluated for impairment	2,261	2,261	3,524	556
Ending Balance	30,124	30,124	75,126	58,279
Ending Balance: individually evaluated for impairment	20,393	20,393	40,345	45,944
Ending Balance: collectively evaluated for impairment	9,731	9,731	34,781	12,335
Residential Real Estate Loans [Member]
Balance, beginning of year	2,555	2,855	1,897	1,897
Provision charged to expense	753	1,173	1,461	4,489
Less: loans charged off	457	1,194	1,438	3,541
Recoveries	18	35	8	10
Balance, end of period	2,869	2,869	1,928	2,855
Ending Balance: individually evaluated for impairment	1,727	1,727	757	1,584
Ending Balance: collectively evaluated for impairment	1,142	1,142	1,171	1,271
Ending Balance	94,129	94,129	86,673	97,172
Ending Balance: individually evaluated for impairment	9,547	9,547	9,899	11,291
Ending Balance: collectively evaluated for impairment	84,582	84,582	76,774	85,881
Consumer Loans [Member]
Balance, beginning of year	1,316	1,338	1,595	1,595
Provision charged to expense	346	510	124	1,175
Less: loans charged off	445	667	682	1,667
Recoveries	58	94	83	235
Balance, end of period	1,275	1,275	1,120	1,338
Ending Balance: individually evaluated for impairment	187	187	298	219
Ending Balance: collectively evaluated for impairment	1,088	1,088	822	1,119
Ending Balance	41,196	41,196	50,801	46,084
Ending Balance: individually evaluated for impairment	1,067	1,067	1,066	1,680
Ending Balance: collectively evaluated for impairment	40,129	40,129	49,735	44,404
Unallocated [Member]
Balance, beginning of year	16		38	38
Provision charged to expense	(7)	9	(12)	(38)
Balance, end of period	9	9	26
Ending Balance: individually evaluated for impairment	0	0
Ending Balance: collectively evaluated for impairment	$ 9	$ 9	$ 26