Note 1 - Fair Value of Financial Assets and Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets, fair value	$ 9,353	$ 8,954
Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
Assets, fair value
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	$ 9,353	$ 8,954
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Assets, fair value
Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Assets, fair value	$ 14,412	$ 30,872
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	14,412	30,872
Money Market Funds [Member]
Assets, fair value	9,353	8,954
Commercial Paper [Member]
Assets, fair value	14,412	30,872
Assets, fair value	$ 23,765	$ 39,826