Note 5 - Loans and Allowance for Loan Losses (Detail) - Activity in the Allowance for Loan Losses Continued (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Individually evaluated for impairment	$ 1,637	$ 715
Collectively evaluated for impairment	8,125	8,909
Total	9,762	9,624	9,556	10,154
Purchased credit-impaired	987	967
Individually evaluated for impairment	17,252	17,742
Collectively evaluated for impairment	1,096,743	1,105,292
Total	1,113,995	1,123,034
Purchased credit-impaired	215,963	234,282
Including Purchased Credit Impaired Loans [Member] | Commercial and Industrial [Member]
Total	1,676	1,074
Total	118,796	119,132
Including Purchased Credit Impaired Loans [Member] | Commercial Real Estate Owner Occupied [Member]
Total	322	496
Total	285,353	299,416
Including Purchased Credit Impaired Loans [Member] | Commercial Real Estate Investor Income Producing [Member]
Total	1,235	1,102
Total	367,434	371,957
Including Purchased Credit Impaired Loans [Member] | Acquisition, Construction, and Development Portfolio [Member]
Total	4,603	4,699
Total	140,869	140,661
Including Purchased Credit Impaired Loans [Member] | Other Commercial [Member]
Total	6	8
Total	4,894	5,628
Including Purchased Credit Impaired Loans [Member] | Residential Mortgage Loans [Member]
Total	667	654
Total	180,368	188,532
Including Purchased Credit Impaired Loans [Member] | Home Equity Lines of Credit [Member]
Total	1,443	1,463
Total	156,802	163,625
Including Purchased Credit Impaired Loans [Member] | Residential Construction [Member]
Total	695	1,046
Total	55,205	52,812
Including Purchased Credit Impaired Loans [Member] | Other Loans to Individuals [Member]
Total	102	49
Total	20,237	15,553
Including Purchased Credit Impaired Loans [Member]
Total	10,749	10,591
Total	1,329,958	1,357,316
Commercial and Industrial [Member]
Individually evaluated for impairment	767	115
Collectively evaluated for impairment	909	734
Total	1,676	849	972	703
Purchased credit-impaired		225
Individually evaluated for impairment	1,625	607
Collectively evaluated for impairment	110,628	111,202
Total	112,253	111,809
Purchased credit-impaired	6,543	7,323
Commercial Real Estate Owner Occupied [Member]
Collectively evaluated for impairment	322	496
Total	322	496	758	740
Individually evaluated for impairment	2,322	2,337
Collectively evaluated for impairment	240,963	252,154
Total	243,285	254,491
Purchased credit-impaired	42,068	44,925
Commercial Real Estate Investor Income Producing [Member]
Individually evaluated for impairment	190
Collectively evaluated for impairment	1,045	1,102
Total	1,235	1,102	1,845	2,106
Individually evaluated for impairment	3,878	4,243
Collectively evaluated for impairment	285,812	281,755
Total	289,690	285,998
Purchased credit-impaired	77,744	85,959
Acquisition, Construction, and Development Portfolio [Member]
Collectively evaluated for impairment	4,218	4,157
Total	4,218	4,157	3,211	3,883
Purchased credit-impaired	385	542
Individually evaluated for impairment	3,547	4,855
Collectively evaluated for impairment	101,014	96,265
Total	104,561	101,120
Purchased credit-impaired	36,308	39,541
Other Commercial [Member]
Collectively evaluated for impairment	6	8
Total	6	8	11	17
Individually evaluated for impairment	164	168
Collectively evaluated for impairment	4,721	4,718
Total	4,885	4,886
Purchased credit-impaired	9	742
Residential Mortgage Loans [Member]
Individually evaluated for impairment	247	249
Collectively evaluated for impairment	102	205
Total	349	454	300	309
Purchased credit-impaired	318	200
Individually evaluated for impairment	3,559	3,463
Collectively evaluated for impairment	137,709	144,586
Total	141,268	148,049
Purchased credit-impaired	39,100	40,483
Home Equity Lines of Credit [Member]
Individually evaluated for impairment	433	351
Collectively evaluated for impairment	1,007	1,112
Total	1,440	1,463	1,698	1,898
Purchased credit-impaired	3
Individually evaluated for impairment	2,087	1,925
Collectively evaluated for impairment	152,760	159,751
Total	154,847	161,676
Purchased credit-impaired	1,955	1,949
Residential Construction [Member]
Collectively evaluated for impairment	450	1,046
Total	450	1,046	572	455
Purchased credit-impaired	245
Individually evaluated for impairment	2	71
Collectively evaluated for impairment	44,607	41,476
Total	44,609	41,547
Purchased credit-impaired	10,596	11,265
Other Loans to Individuals [Member]
Collectively evaluated for impairment	66	49
Total	66	49	39	43
Purchased credit-impaired	36
Individually evaluated for impairment	68	73
Collectively evaluated for impairment	18,529	13,385
Total	18,597	13,458
Purchased credit-impaired	$ 1,640	$ 2,095