Note 7 - Investments in Marketable Securities (Details) - Amortized Cost and Estimated Fair Value of Debt Securities as Available for Sale - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Maturities:
Within 1 year	$ 14,507	$ 11,161
Within 1 year	14,551	11,190
1 to 5 years	77,956	83,542
1 to 5 years	78,605	84,028
6 to 10 years	70,985	58,863
6 to 10 years	70,113	58,872
Over 10 years	2,271	4,076
Over 10 years	2,204	4,183
	165,719	157,642
	$ 165,473	$ 158,273