Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) shares in Thousands, $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Accounts receivable, allowance	$ 0.2	$ 0.2
Preferred stock, par value (in dollars per share)	$ 0.00015	$ 0.00015
Preferred stock, shares authorized (in shares)	5,000	5,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.00015	$ 0.00015
Common stock, shares authorized (in shares)	70,000	70,000
Common stock, shares issued (in shares)	38,810	38,514
Common stock, shares outstanding (in shares)	32,124	31,864
Treasury stock, shares (in shares)	6,687	6,650