Basis and Summary of Significant Accounting Policies - Calculation of Dilutive Stock Awards (Details) - shares shares in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Policies [Abstract]
Weighted Average Shares Outstanding (in shares)	68,819	70,746	69,521	70,914
Dilutive Effect of Share-Based Awards (in shares)	1,320	1,349	1,475	1,143
Weighted Average Shares Outstanding Assuming Dilution (in shares)	70,139	72,095	70,996	72,057
Anti-dilutive securities excluded from the computation of earnings per share assuming dilution (in shares)	356	9	345	180

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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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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-Publisher FASB
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-Topic 260
-SubTopic 10
-Section 50
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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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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