Stock-Based Compensation (Summary of Equity-Classified Stock Option Activity) (Details) - Stock options shares in Thousands	6 Months Ended
Jun. 30, 2019 $ / shares shares
Number of Options
Beginning balance (in shares) \| shares	5,178
Granted (in shares) \| shares	0
Exercised (in shares) \| shares	0
Forfeited or expired (in shares) \| shares	(72)
Ending balance (in shares) \| shares	5,106
Exercisable (in shares) \| shares	4,590
Weighted Average Exercise Price
Beginning balance (in dollars per share) \| $ / shares	$ 17.06
Granted (in dollars per share) \| $ / shares	0
Exercised (in dollars per share) \| $ / shares	0
Forfeited or expired (in dollars per share) \| $ / shares	18.58
Ending balance (in dollars per share) \| $ / shares	17.04
Exercisable (in dollars per share) \| $ / shares	$ 18.12

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Net number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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