Stock-Based Compensation, Stock-based Comp Expense (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock-Based Compensation
Expense incurred for stock-based compensation plans	$ 20.0	$ 16.6	$ 39.0	$ 32.0
Recognized tax benefit related to stock-based compensation	21.8	14.3	26.4	21.1
Excess tax benefit from option exercises	$ 19.3	$ 12.4	$ 22.0	$ 17.4

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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