Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts	$ 4,175	$ 3,936
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	145,000	145,000
Common stock, shares issued (in shares)	53,610	53,268
Common stock, shares outstanding (in shares)	53,610	53,268

Amount of allowance for credit loss on accounts receivable, classified as current.

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