Note 8 - Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2018

Notes Tables

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

	As of September 30, 2018
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets	Total		(Level 1)		(Level 2)		(Level 3)
Money market mutual funds	$	26,934	$	26,934	$	—	$	—

	As of December 31, 2017
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets	Total		(Level 1)		(Level 2)		(Level 3)
Money market mutual funds	$	26,638	$	26,638	$	—	$	—