Note 5 - Loans Held for Investment (Detail) - Impaired Loans (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	$ 421	$ 1,815
Interest Income Recognized on Impaired Loans	54	220
Totals:
Contractual Unpaid Principal Balance	437,518		526,800
Interest Income Recognized on Impaired Loans	475	2,035
Commercial Real Estate Loans [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	22,467	25,703
Recorded Investment	2,677	1,912
Commercial Real Estate Loans [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	23,418	27,400
Contractual Unpaid Principal Balance	2,963	1,912
Commercial Real Estate Loans [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	420	35
Totals:
Related Allowance	420	35
Commercial Real Estate Loans [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	24,085	33,191
YTD Average Recorded Investment	2,295	3,420
Commercial Real Estate Loans [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	315	1,504
Interest Income Recognized on Impaired Loans	38	116
Commercial Construction [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	731	382
Commercial Construction [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	731	382
Commercial Construction [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	557	2,125
Commercial Construction [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	7	14
Commercial Lots and Raw Land [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	5,970	5,963
Recorded Investment	997	1,915
Commercial Lots and Raw Land [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	5,970	5,963
Contractual Unpaid Principal Balance	997	1,915
Commercial Lots and Raw Land [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	212	303
Totals:
Related Allowance	212	303
Commercial Lots and Raw Land [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	5,966	13,894
YTD Average Recorded Investment	1,456	2,070
Commercial Lots and Raw Land [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	86	262
Interest Income Recognized on Impaired Loans	6	70
Commercial and Industrial [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment		126
Recorded Investment	126
Commercial and Industrial [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance		126
Contractual Unpaid Principal Balance	126
Commercial and Industrial [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	0
Totals:
Related Allowance	0
Commercial and Industrial [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment		1,284
YTD Average Recorded Investment	126
Commercial and Industrial [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans		6
Interest Income Recognized on Impaired Loans	2
Consumer Real Estate Loans [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	480	373
Recorded Investment	52	69
Consumer Real Estate Loans [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	480	373
Contractual Unpaid Principal Balance	52	69
Consumer Real Estate Loans [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	1	12
Totals:
Related Allowance	1	12
Consumer Real Estate Loans [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	427	584
YTD Average Recorded Investment	61	162
Consumer Real Estate Loans [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	7	20
Interest Income Recognized on Impaired Loans	1	4
Consumer Lots and Raw Land [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	340	342
Recorded Investment	730	582
Consumer Lots and Raw Land [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	340	342
Contractual Unpaid Principal Balance	730	582
Consumer Lots and Raw Land [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	179	110
Totals:
Related Allowance	179	110
Consumer Lots and Raw Land [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	341	545
YTD Average Recorded Investment	656	632
Consumer Lots and Raw Land [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	1	4
Interest Income Recognized on Impaired Loans	9	28
Home equity lines of credit [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	36	38
Home equity lines of credit [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	36	38
Home equity lines of credit [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	37	154
Home equity lines of credit [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	1	2
Consumer Other [Member] | Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	119	73
Recorded Investment	10	47
Consumer Other [Member] | Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	141	147
Contractual Unpaid Principal Balance	10	47
Consumer Other [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	10	0
Totals:
Related Allowance	10	0
Consumer Other [Member] | YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	96	51
YTD Average Recorded Investment	5	71
Consumer Other [Member]
With no related allowance recorded:
Interest Income Recognized on Impaired Loans	2	3
Interest Income Recognized on Impaired Loans		2
Commercial total [Member] | Recorded Investment [Member]
Totals:
Recorded Investment	32,968	36,001
Commercial total [Member] | Contractual Unpaid Principal Balance [Member]
Totals:
Contractual Unpaid Principal Balance	34,205	37,698
Commercial total [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	632	338
Totals:
Related Allowance	632	338
Commercial total [Member] | YTD Average Recorded Investment [Member]
Totals:
YTD Average Recorded Investment	34,485	55,984
Commercial total [Member]
Totals:
Interest Income Recognized on Impaired Loans	454	1,972
Consumer total [Member] | Recorded Investment [Member]
Totals:
Recorded Investment	1,767	1,524
Consumer total [Member] | Contractual Unpaid Principal Balance [Member]
Totals:
Contractual Unpaid Principal Balance	1,789	1,598
Consumer total [Member] | Related Allowance [Member]
With no related allowance recorded:
Related Allowance	190	122
Totals:
Related Allowance	190	122
Consumer total [Member] | YTD Average Recorded Investment [Member]
Totals:
YTD Average Recorded Investment	1,623	2,199
Consumer total [Member]
Totals:
Interest Income Recognized on Impaired Loans	21	63
Recorded Investment [Member]
With no related allowance recorded:
Recorded Investment	30,269	33,000
Recorded Investment	4,466	4,525
Totals:
Recorded Investment	34,735	37,525
Contractual Unpaid Principal Balance [Member]
With no related allowance recorded:
Contractual Unpaid Principal Balance	31,242	34,771
Contractual Unpaid Principal Balance	4,752	4,525
Totals:
Contractual Unpaid Principal Balance	35,994	39,296
Related Allowance [Member]
With no related allowance recorded:
Related Allowance	822	460
Totals:
Related Allowance	822	460
YTD Average Recorded Investment [Member]
With no related allowance recorded:
YTD Average Recorded Investment	31,635	51,828
YTD Average Recorded Investment	4,473	6,355
Totals:
YTD Average Recorded Investment	$ 36,108	$ 58,183