Stock-Based Compensation, Stock-based Comp Expense (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Stock-Based Compensation
Expense incurred for stock-based compensation plans	$ 19.1	$ 15.4
Recognized tax benefit related to stock-based compensation	4.5	6.8
Excess tax benefit from option exercises	$ 2.6	$ 5.0

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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