Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value	$ 444,607	$ 424,716
Available for sale securities, less than 12 months, unrealized losses	(10,718)	(14,322)
Available for sale securities, 12 months or longer, fair value	139,136	59,930
Available for sale securities, 12 months or longer, unrealized losses	(4,189)	(2,934)
Available for sale securities, total, fair value	583,743	484,646
Available for sale securities, total, unrealized losses	(14,907)	(17,256)
Held to maturity securities, less than 12 months, fair value	435,488	610,771
Held to maturity securities, less than 12 months, unrealized losses	(8,144)	(20,688)
Held to maturity securities, 12 months or longer, fair value	159,666	78,939
Held to maturity securities, 12 months or longer, unrealized losses	(8,249)	(7,209)
Held to maturity securities, total, fair value	595,154	689,710
Held to maturity securities, total, unrealized losses	(16,393)	(27,897)
US Government-sponsored Enterprises Debt Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value	239,558	91,669
Available for sale securities, less than 12 months, unrealized losses	(1,360)	(663)
Available for sale securities, 12 months or longer, fair value	8,968
Available for sale securities, 12 months or longer, unrealized losses	(27)
Available for sale securities, total, fair value	248,526	91,669
Available for sale securities, total, unrealized losses	(1,387)	(663)
Held to maturity securities, less than 12 months, fair value	1,424	1,597
Held to maturity securities, less than 12 months, unrealized losses	(4)	(4)
Held to maturity securities, total, fair value	1,424	1,597
Held to maturity securities, total, unrealized losses	(4)	(4)
Residential Mortgage Backed Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value		864
Available for sale securities, less than 12 months, unrealized losses		(15)
Available for sale securities, 12 months or longer, fair value	848
Available for sale securities, 12 months or longer, unrealized losses	(18)
Available for sale securities, total, fair value	848	864
Available for sale securities, total, unrealized losses	(18)	(15)
Held to maturity securities, less than 12 months, fair value	29,321	38,396
Held to maturity securities, less than 12 months, unrealized losses	(276)	(616)
Held to maturity securities, 12 months or longer, fair value	7,235	392
Held to maturity securities, 12 months or longer, unrealized losses	(112)	(8)
Held to maturity securities, total, fair value	36,556	38,788
Held to maturity securities, total, unrealized losses	(388)	(624)
Commercial Mortgage Backed Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value	960	1,072
Available for sale securities, less than 12 months, unrealized losses	(5)	(5)
Available for sale securities, total, fair value	960	1,072
Available for sale securities, total, unrealized losses	(5)	(5)
US States and Political Subdivisions Debt Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value	11,098	17,516
Available for sale securities, less than 12 months, unrealized losses	(123)	(222)
Available for sale securities, 12 months or longer, fair value	3,683	3,214
Available for sale securities, 12 months or longer, unrealized losses	(99)	(101)
Available for sale securities, total, fair value	14,781	20,730
Available for sale securities, total, unrealized losses	(222)	(323)
Held to maturity securities, less than 12 months, fair value	201,958	355,797
Held to maturity securities, less than 12 months, unrealized losses	(3,292)	(14,893)
Held to maturity securities, 12 months or longer, fair value	150,776	64,427
Held to maturity securities, 12 months or longer, unrealized losses	(8,117)	(6,774)
Held to maturity securities, total, fair value	352,734	420,224
Held to maturity securities, total, unrealized losses	(11,409)	(21,667)
Residential Collateralized Mortgage Obligations [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value	154,576	187,848
Available for sale securities, less than 12 months, unrealized losses	(9,107)	(12,326)
Available for sale securities, 12 months or longer, fair value	68,889	40,575
Available for sale securities, 12 months or longer, unrealized losses	(3,353)	(2,398)
Available for sale securities, total, fair value	223,465	228,423
Available for sale securities, total, unrealized losses	(12,460)	(14,724)
Held to maturity securities, less than 12 months, fair value	202,785	214,981
Held to maturity securities, less than 12 months, unrealized losses	(4,572)	(5,175)
Held to maturity securities, 12 months or longer, fair value	1,655	14,120
Held to maturity securities, 12 months or longer, unrealized losses	(20)	(427)
Held to maturity securities, total, fair value	204,440	229,101
Held to maturity securities, total, unrealized losses	(4,592)	(5,602)
Asset-backed Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value		5,002
Available for sale securities, less than 12 months, unrealized losses		(1)
Available for sale securities, 12 months or longer, fair value	4,205	4,475
Available for sale securities, 12 months or longer, unrealized losses	(56)	(100)
Available for sale securities, total, fair value	4,205	9,477
Available for sale securities, total, unrealized losses	(56)	(101)
Domestic Corporate Debt Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value	38,415	117,751
Available for sale securities, less than 12 months, unrealized losses	(123)	(1,087)
Available for sale securities, 12 months or longer, fair value	50,693	9,824
Available for sale securities, 12 months or longer, unrealized losses	(486)	(177)
Available for sale securities, total, fair value	89,108	127,575
Available for sale securities, total, unrealized losses	(609)	(1,264)
Other Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, 12 months or longer, fair value	1,850	1,842
Available for sale securities, 12 months or longer, unrealized losses	(150)	(158)
Available for sale securities, total, fair value	1,850	1,842
Available for sale securities, total, unrealized losses	(150)	(158)
US Treasury Securities [Member]
Note 3 - Investment Securities (Details) - Gross Unrealized Losses - Investments [Line Items]
Available for sale securities, less than 12 months, fair value		2,994
Available for sale securities, less than 12 months, unrealized losses		(3)
Available for sale securities, total, fair value		2,994
Available for sale securities, total, unrealized losses		$ (3)