Note 6 - Investment Securities (Details) - Investments by Contractual Maturity Date (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Investments by Contractual Maturity Date [Abstract]
Due in one year or less	$ 174,987
Due in one year or less	175,062
Due after one year through five years	194,247
Due after one year through five years	195,198
Due after five years through ten years	65,595
Due after five years through ten years	65,057
Due after ten years (1)	763,093	[1]
Due after ten years (1)	768,365	[1]
Total	1,197,922		1,324,408
Total	$ 1,203,682		$ 1,318,935

[1] Equity securities are reported in this category