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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of stock repurchase plan authorized.

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Equity - Share Repurchases, Dividends, Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended						9 Months Ended
	Oct. 26, 2021	Mar. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Jul. 20, 2021
Share Repurchase Plan
Value of shares authorized by the Board of Directors to be repurchased under share repurchase plan											$ 1,000.0
Share repurchases (in shares)			885,606			2,466			1,000,000.0	3,300,000
Average costs per share			$ 147.89			$ 100.00			$ 150.12	$ 90.10
Value of shares repurchased			$ 131.0	$ 24.0		$ 0.2		$ 300.0	$ 155.0	$ 300.2
Dividends
Common stock quarterly dividend per share (in dollars per share)	$ 0.6875		$ 0.6875	$ 0.6875	$ 0.6875	$ 0.625	$ 0.625	$ 0.625
Common stock dividend quarterly declared and paid per share (in dollars per share)			$ 0.6875			$ 0.6250			$ 2.0625	$ 1.8750
Dividends paid			$ 43.6			$ 39.8			$ 131.2	$ 120.7
Common Stock and Additional Paid in Capital
Share Repurchase Plan
Value of shares repurchased			$ 21.9	$ 24.0		$ 0.2		$ 119.3
Common Stock and Additional Paid-In (in Shares)
Payments made to tax authorities on employees' behalf									9.2	14.9
RSU's
Dividends
Dividend equivalents paid									$ 1.1	$ 2.1
Stock-Based Compensation
Vesting period (in years)									3 years
RSU's \| Service-based
Stock-Based Compensation
Vesting period (in years)		3 years
Changes
Granted (in shares)		191,139
Weighted Average Grant Date Fair Value
Granted (in dollars per share)		$ 141.41
RSU's \| Performance-based
Stock-Based Compensation
Vesting period (in years)		3 years
Changes
Granted (in shares)		127,356
Weighted Average Grant Date Fair Value
Granted (in dollars per share)		$ 141.41
Unvested RSUs
Changes
Unvested at the beginning of the year (in shares)					995,720				995,720
Granted (in shares)									318,495
Vested (in shares)									(7,812)
Cancelled or forfeited (in shares)									(19,107)
Unvested at the end of the period (in shares)			1,287,296						1,287,296
Shares reserved for future grants (all plans)			1,877,393						1,877,393
Weighted Average Grant Date Fair Value
Unvested at the beginning of the year (in dollars per share)					$ 85.27				$ 85.27
Granted (in dollars per share)									141.41
Vested (in dollars per share)									86.52
Cancelled or forfeited (in dollars per share)									89.99
Unvested at the end of the period (in dollars per share)			$ 99.08						$ 99.08