Note 3 - Securities (Details) - Remaining Contractual Maturity of Securities (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Available-for-sale Securities, Amortized Cost Basis [Abstract]
One year or less	$ 5,078
After one year to five years	293,418
After five years to ten years	121,548
After ten years	104,165
Securities that do not have a single contractual maturity	665,531
Total	1,189,740	1,080,574
Available-for-sale Securities, Fair Value [Abstract]
One year or less	4,880
After one year to five years	281,966
After five years to ten years	116,804
After ten years	100,099
Securities that do not have a single contractual maturity	659,162
Total securities available-for-sale	1,162,911	1,082,403
Held-to-maturity Securities, Amortized Cost [Abstract]
One year or less	3,185
After one year to five years	6,540
After five years to ten years	10,274
After ten years	9,848
Securities that do not have a single contractual maturity	0
Total	29,847	34,295
Held-to-maturity Securities, Fair Value [Abstract]
One year or less	3,153
After one year to five years	6,473
After five years to ten years	10,169
After ten years	9,747
Securities that do not have a single contractual maturity	0
Total	$ 29,542	$ 36,023