Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Allowances for Accounts Receivable (in dollars)	$ 884	$ 616	$ 612
Preferred stock-issued	0	0	0
Common stock par value	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized	135,000,000	135,000,000	135,000,000
Common stock, shares issued	87,507,000	87,306,000	86,655,000
Common stock, shares outstanding	58,332,000	58,698,000	59,736,000
Treasury stock-shares at cost	29,175,000	28,608,000	26,919,000
Preferred Class A [Member]
Preferred stock-par value	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock- shares authorized	5,000,000	5,000,000	5,000,000
Preferred Class B [Member]
Preferred stock-par value	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock- shares authorized	60,000	60,000	60,000

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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