Note 3 - Investment Securities (Details) - Gross Unrealized Losses and Fair Value of Investments With Unrealized Losses in a Continuous Unrealized Loss Position: (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Held-to-Maturity
Held-to-Maturity Securities Less Than 12 Months Estimated Fair Value	$ 420,984	$ 209,881
Held-to-Maturity Securities Less Than 12 Months Gross Unrealized Losses	12,158	749
Held-to-Maturity Securities 12 Months or More Estimated Fair Value	118,805	511
Held-to-Maturity Securities 12 Months or More Gross Unrealized Losses	4,317	90
Held-to-Maturity Securities Estimated Fair Value	539,790	210,392
Held-to-Maturity Securities Gross Unrealized Losses	16,475	839
Available-for-Sale
Available-for-Sale Securities Less Than 12 Months Estimated Fair Value	119,141	121,644
Available-for-Sale Securities Less Than 12 Months Gross Unrealized Losses	2,703	385
Available-for-Sale Securities 12 Months or More Estimated Fair Value	56,396	25
Available-for-Sale Securities 12 Months or More Estimated Fair Value	2,890	1
Available-for-Sale Securities Estimated Fair Value	175,537	121,669
Available-for-Sale Securities Gross Unrealized Losses	5,592	386
US Government Agencies Debt Securities [Member]
Held-to-Maturity
Held-to-Maturity Securities Less Than 12 Months Estimated Fair Value	258,474	196,783
Held-to-Maturity Securities Less Than 12 Months Gross Unrealized Losses	6,405	679
Held-to-Maturity Securities 12 Months or More Estimated Fair Value	114,339
Held-to-Maturity Securities 12 Months or More Gross Unrealized Losses	4,130
Held-to-Maturity Securities Estimated Fair Value	372,814	196,783
Held-to-Maturity Securities Gross Unrealized Losses	10,535	679
Available-for-Sale
Available-for-Sale Securities Less Than 12 Months Estimated Fair Value	111,662	105,994
Available-for-Sale Securities Less Than 12 Months Gross Unrealized Losses	2,682	292
Available-for-Sale Securities 12 Months or More Estimated Fair Value	56,396
Available-for-Sale Securities 12 Months or More Estimated Fair Value	2,890
Available-for-Sale Securities Estimated Fair Value	168,058	105,994
Available-for-Sale Securities Gross Unrealized Losses	5,572	292
Collateralized Mortgage Backed Securities [Member]
Held-to-Maturity
Held-to-Maturity Securities Less Than 12 Months Estimated Fair Value	32,053
Held-to-Maturity Securities Less Than 12 Months Gross Unrealized Losses	442
Held-to-Maturity Securities Estimated Fair Value	32,053
Held-to-Maturity Securities Gross Unrealized Losses	442
Available-for-Sale
Available-for-Sale Securities Less Than 12 Months Estimated Fair Value		14,420
Available-for-Sale Securities Less Than 12 Months Gross Unrealized Losses		88
Available-for-Sale Securities 12 Months or More Estimated Fair Value		25
Available-for-Sale Securities 12 Months or More Estimated Fair Value		1
Available-for-Sale Securities Estimated Fair Value		14,445
Available-for-Sale Securities Gross Unrealized Losses		89
US States and Political Subdivisions Debt Securities [Member]
Held-to-Maturity
Held-to-Maturity Securities Less Than 12 Months Estimated Fair Value	130,457	13,098
Held-to-Maturity Securities Less Than 12 Months Gross Unrealized Losses	5,311	70
Held-to-Maturity Securities 12 Months or More Estimated Fair Value	4,466	511
Held-to-Maturity Securities 12 Months or More Gross Unrealized Losses	187	90
Held-to-Maturity Securities Estimated Fair Value	134,923	13,609
Held-to-Maturity Securities Gross Unrealized Losses	5,498	160
Available-for-Sale
Available-for-Sale Securities Less Than 12 Months Estimated Fair Value	2,921	1,229
Available-for-Sale Securities Less Than 12 Months Gross Unrealized Losses	3	1
Available-for-Sale Securities Estimated Fair Value	2,921	1,229
Available-for-Sale Securities Gross Unrealized Losses	3	1
US Treasury Securities [Member]
Available-for-Sale
Available-for-Sale Securities Less Than 12 Months Estimated Fair Value	3,985
Available-for-Sale Securities Less Than 12 Months Gross Unrealized Losses	16
Available-for-Sale Securities Estimated Fair Value	3,985
Available-for-Sale Securities Gross Unrealized Losses	16
Other Securities [Member]
Available-for-Sale
Available-for-Sale Securities Less Than 12 Months Estimated Fair Value	573	1
Available-for-Sale Securities Less Than 12 Months Gross Unrealized Losses	1	4
Available-for-Sale Securities Estimated Fair Value	573	1
Available-for-Sale Securities Gross Unrealized Losses	$ 1	$ 4