Net Earnings Per Share Net Earnings Per Share (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net Income (loss) Available to Common Stockholders, Basic	$ 61,748	$ 39,195
Weighted Average Number of Shares Outstanding, Basic	135,541	138,504
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	1,624	2,490
Weighted Average Number of Shares Outstanding, Diluted	137,165	140,994

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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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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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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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