Stock-Based Compensation (Stock Units Converted To Common Stock) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total intrinsic value of vested stock units converted to common stock	$ 12.1	$ 22.7	$ 24.8

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Fully Vested, Intrinsic Value, Total

No definition available.

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