Stock-Based Compensation (Stock Units Converted To Common Stock) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
Share-based Payment Arrangement [Abstract] | |||
Total intrinsic value of vested stock units converted to common stock | $ 8.0 | $ 12.1 | $ 22.7 |