Note 3 - Fair Value Measurement - Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets:
Cash and cash equivalents	$ 19,032	$ 21,352
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash and cash equivalents	19,032	21,352
Fair Value, Inputs, Level 2 [Member]
Assets:
Cash and cash equivalents
Fair Value, Inputs, Level 3 [Member]
Assets:
Cash and cash equivalents