Note 7 - Investment Securities (Details) - Investments by Contractual Maturity Date - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Investments by Contractual Maturity Date [Abstract]
Due in one year or less		$ 184,935
Due in one year or less		185,127
Due after one year through five years		136,610
Due after one year through five years		137,407
Due after five years through ten years		45,546
Due after five years through ten years		44,172
Due after ten years (1)	[1]	1,010,997
Due after ten years (1)	[1]	1,014,173
Total		1,378,088	$ 1,324,408
Total		$ 1,380,879	$ 1,318,935

[1] Equity securities are reported in this category