Shareholders' Equity (Stock Option Activity) (Details)	9 Months Ended
Sep. 30, 2018 $ / shares shares
Shares Underlying Stock Options
Outstanding beginning balance, Shares underlying stock options and restricted stock awards (in shares) \| shares	6,037,302
Granted, Shares underlying stock options and restricted stock awards (in shares) \| shares	1,130,700
Exercised, Shares underlying stock options and restricted stock awards (in shares) \| shares	(106,370)
Forfeited, Shares underlying stock options and restricted stock awards (in shares) \| shares	(293,368)
Outstanding ending balance, Shares underlying stock options and restricted stock awards (in shares) \| shares	6,768,264
Weighted- Average Exercise Price per Share
Outstanding beginning balance, Weighted - average exercise price (usd per share) \| $ / shares	$ 24.19
Granted, Weighted - average exercise price (usd per share) \| $ / shares	29.48
Exercised, Weighted - average exercise price (usd per share) \| $ / shares	17.95
Forfeited, Weighted - average exercise price (usd per share) \| $ / shares	26.94
Outstanding ending balance, Weighted - average exercise price (usd per share) \| $ / shares	$ 25.05

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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Gross 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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-Publisher FASB
-Name Accounting Standards Codification
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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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