Note 1 - Basis of Presentation - Reconciliation of Basic to Diluted Weighted-average Shares Outstanding (Details) - shares shares in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted-average shares outstanding-basic (in shares)	87,765	71,821	88,408	71,849
Common stock equivalents for stock options and restricted shares (in shares)	540	680	529	661
Weighted-average shares outstanding-diluted (in shares)	88,305	72,501	88,937	72,510

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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