Note 5 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	May 29, 2018	Mar. 31, 2020	Mar. 31, 2019
Treasury Stock, Value, Acquired, Cost Method			$ 3,917
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 15,200
The 2018 Stock Repurchase Program [Member]
Stock Repurchase Program, Authorized Amount	$ 25,000
Stock Repurchase Program, Period in Force (Year)	2 years
Treasury Stock, Shares, Acquired (in shares)		0	314,000
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)			$ 12.46
Treasury Stock, Value, Acquired, Cost Method			$ 3,900