Note 3 - Investment Securities (Details) - Amortized Cost, Unrealized Gains and Losses, and Fair Value - Held to Maturity Investment Securities Portfolio (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Note 3 - Investment Securities (Details) - Amortized Cost, Unrealized Gains and Losses, and Fair Value - Held to Maturity Investment Securities Portfolio [Line Items]
Amortized Cost	$ 1,035,041	$ 1,132,299
Gross Unrealized Gains	14,082	8,274
Gross Unrealized Losses	(7,738)	(27,897)
Fair Value	1,041,385	1,112,676
US Government-sponsored Enterprises Debt Securities [Member]
Note 3 - Investment Securities (Details) - Amortized Cost, Unrealized Gains and Losses, and Fair Value - Held to Maturity Investment Securities Portfolio [Line Items]
Amortized Cost	1,164	1,601
Gross Unrealized Losses		(4)
Fair Value	1,164	1,597
Residential Mortgage Backed Securities [Member]
Note 3 - Investment Securities (Details) - Amortized Cost, Unrealized Gains and Losses, and Fair Value - Held to Maturity Investment Securities Portfolio [Line Items]
Amortized Cost	59,182	65,076
Gross Unrealized Gains	926	854
Gross Unrealized Losses	(86)	(624)
Fair Value	60,022	65,306
US States and Political Subdivisions Debt Securities [Member]
Note 3 - Investment Securities (Details) - Amortized Cost, Unrealized Gains and Losses, and Fair Value - Held to Maturity Investment Securities Portfolio [Line Items]
Amortized Cost	703,554	756,707
Gross Unrealized Gains	11,483	6,211
Gross Unrealized Losses	(2,909)	(21,667)
Fair Value	712,128	741,251
Residential Collateralized Mortgage Obligations [Member]
Note 3 - Investment Securities (Details) - Amortized Cost, Unrealized Gains and Losses, and Fair Value - Held to Maturity Investment Securities Portfolio [Line Items]
Amortized Cost	271,141	308,915
Gross Unrealized Gains	1,673	1,209
Gross Unrealized Losses	(4,743)	(5,602)
Fair Value	$ 268,071	$ 304,522