Note 4 - Investment Securities (Detail) - Schedule of amortized cost, unrealized gains and losses accumulated in other comprehensive income, and fair value - available for sale investment securities portfolio (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Amortized Cost	$ 664,627	$ 670,778
Gross Unrealized Gains	21,730	10,569
Gross Unrealized Losses	(2,717)	(9,863)
Fair Value	683,640	671,484
US Treasury Securities [Member]
Amortized Cost	3,541	3,554
Gross Unrealized Gains	59
Gross Unrealized Losses		(12)
Fair Value	3,600	3,542
US Government-sponsored Enterprises Debt Securities [Member]
Amortized Cost	128,157	175,080
Gross Unrealized Gains	383	162
Gross Unrealized Losses	(42)	(2,365)
Fair Value	128,498	172,877
Residential Mortgage Backed Securities [Member]
Amortized Cost	93,328	105,702
Gross Unrealized Gains	5,984	4,142
Gross Unrealized Losses	(6)	(15)
Fair Value	99,306	109,829
Commercial Mortgage Backed Securities [Member]
Amortized Cost	4,606	5,081
Gross Unrealized Gains	24	7
Gross Unrealized Losses	(6)	(23)
Fair Value	4,624	5,065
US States and Political Subdivisions Debt Securities [Member]
Amortized Cost	257,481	264,757
Gross Unrealized Gains	8,801	2,423
Gross Unrealized Losses	(471)	(6,047)
Fair Value	265,811	261,133
Residential Collateralized Mortgage Obligations [Member]
Amortized Cost	51,919	24,709
Gross Unrealized Gains	2,384	894
Fair Value	54,303	25,603
Asset-backed Securities [Member]
Amortized Cost	7,933	9,060
Gross Unrealized Losses	(282)	(774)
Fair Value	7,651	8,286
FHLMC And FNMA Stock [Member]
Amortized Cost	824	824
Gross Unrealized Gains	1,968	42
Gross Unrealized Losses	(5)	(211)
Fair Value	2,787	655
Domestic Corporate Debt Securities [Member]
Amortized Cost	114,441	79,356
Gross Unrealized Gains	199	200
Gross Unrealized Losses	(1,863)	(365)
Fair Value	112,777	79,191
Other Securities [Member]
Amortized Cost	2,397	2,655
Gross Unrealized Gains	1,928	2,699
Gross Unrealized Losses	(42)	(51)
Fair Value	$ 4,283	$ 5,303