Note 4 - Loans and Allowance for Credit Losses (Detail) - Loans receivable at carrying amount (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Originated loans	$ 1,613,396	$ 1,664,183
Purchased covered loans	353,034	372,283
Purchased non-covered loans	70,504	74,891
Total	2,036,934	2,111,357
Impaired [Member] | Commercial Portfolio Segment [Member]
Purchased covered loans	293	308
Purchased non-covered loans	1,244	1,261
Impaired [Member] | Commercial Real Estate Portfolio Segment [Member]
Purchased covered loans	6,899	7,585
Purchased non-covered loans	6,111	6,763
Impaired [Member] | Construction Portfolio Segment [Member]
Purchased covered loans	1,737	1,824
Impaired [Member] | Consumer Portfolio Segment [Member]
Purchased covered loans	255	257
Purchased non-covered loans	297	297
Impaired [Member]
Purchased covered loans	9,184	9,974
Purchased non-covered loans	7,652	8,321
Non Impaired [Member] | Commercial Portfolio Segment [Member]
Purchased covered loans	57,589	59,135
Purchased non-covered loans	9,367	9,840
Non Impaired [Member] | Commercial Real Estate Portfolio Segment [Member]
Purchased covered loans	232,854	247,534
Purchased non-covered loans	37,548	38,673
Non Impaired [Member] | Construction Portfolio Segment [Member]
Purchased covered loans	4,942	5,462
Purchased non-covered loans	1,369	1,619
Non Impaired [Member] | Residential Portfolio Segment [Member]
Purchased covered loans	8,816	9,374
Purchased non-covered loans	2,205	3,110
Non Impaired [Member] | Consumer Portfolio Segment [Member]
Purchased covered loans	62,309	66,932
Purchased non-covered loans	16,949	18,554
Non Impaired [Member]
Purchased covered loans	366,510	388,437
Purchased non-covered loans	67,438	71,796
Purchase Discount [Member] | Commercial Portfolio Segment [Member]
Purchased covered loans	(6,958)	(8,459)
Purchased non-covered loans	(913)	(870)
Purchase Discount [Member] | Commercial Real Estate Portfolio Segment [Member]
Purchased covered loans	(13,600)	(15,140)
Purchased non-covered loans	(1,750)	(1,748)
Purchase Discount [Member] | Construction Portfolio Segment [Member]
Purchased covered loans	(188)	(279)
Purchased non-covered loans	(95)	(95)
Purchase Discount [Member] | Residential Portfolio Segment [Member]
Purchased covered loans	(434)	(433)
Purchased non-covered loans	(262)	(474)
Purchase Discount [Member] | Consumer Portfolio Segment [Member]
Purchased covered loans	(1,480)	(1,817)
Purchased non-covered loans	(1,566)	(2,039)
Purchase Discount [Member]
Purchased covered loans	(22,660)	(26,128)
Purchased non-covered loans	(4,586)	(5,226)
Commercial Portfolio Segment [Member]
Originated loans	318,502	340,116
Total	379,124	401,331
Commercial Real Estate Portfolio Segment [Member]
Originated loans	625,185	632,927
Total	893,247	916,594
Construction Portfolio Segment [Member]
Originated loans	7,920	7,984
Total	15,685	16,515
Residential Portfolio Segment [Member]
Originated loans	213,919	222,458
Total	224,244	234,035
Consumer Portfolio Segment [Member]
Originated loans	447,870	460,698
Total	$ 524,634	$ 542,882