Note 1 - Fair Value of Financial Assets and Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets, fair value	$ 8,954	$ 9,442
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	8,954	9,442
Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Assets, fair value	30,872	29,686
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	30,872	29,686
Money Market Funds [Member]
Assets, fair value	8,954	9,442
Commercial Paper [Member]
Assets, fair value	30,872	29,686
Assets, fair value	$ 39,826	$ 39,128