Note 2 - Significant Accounting Policies (Details) - Summary of Available-for-Sale Securities by Contractual Maturity (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Summary of Available-for-Sale Securities by Contractual Maturity [Abstract]    
Less than one year $ 51,338 $ 56,789
Less than one year 51,319 56,806
Greater than one year but less than five years 6,050 12,537
Greater than one year but less than five years 6,044 12,535
Total 57,388 69,326
Total $ 57,363 $ 69,341