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Aggregate dividends paid during the period for each share of common stock outstanding.

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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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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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Equity - Share Repurchases, Dividends, Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions			1 Months Ended	3 Months Ended
	Apr. 21, 2020	Oct. 23, 2018	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019
Share Repurchase Plan
Increase in authorized number of shares to be repurchased		5,000,000.0
Number of shares authorized by the Board of Directors to be repurchased under share repurchase plan			3,100,000	3,100,000
Number of shares authorized by the Board of Directors to be repurchased under share repurchase plan, expressed as a percentage of outstanding shares (as a percent)			5.00%	5.00%
Share repurchases (in shares)				3,300,000	0
Average costs per share				$ 90.09
Value of shares repurchased				$ 300.0
Dividends
Common stock quarterly dividend per share (in dollars per share)	$ 0.625			$ 0.625	$ 0.55
Common stock dividend quarterly declared and paid per share (in dollars per share)				$ 0.625	$ 0.55
Dividends paid				$ 41.0	$ 37.0
Common Stock and Additional Paid in Capital
Share Repurchase Plan
Value of shares repurchased				119.3
Common Stock and Additional Paid-In (in Shares)
Payments made to tax authorities on employees' behalf				5.1	9.5
RSU's
Dividends
Dividend equivalents paid				$ 0.9	$ 2.6
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)			330,144
Weighted Average Grant Date Fair Value
Granted (in dollars per share)			$ 82.81
RSU's \| Performance-based
Stock-Based Compensation
Vesting period (in years)			3 years
Changes
Granted (in shares)			210,403
Weighted Average Grant Date Fair Value
Granted (in dollars per share)			$ 82.81
Unvested RSUs
Changes
Unvested at the beginning of the year (in shares)				859,005
Granted (in shares)				540,547
Vested (in shares)				(721)
Cancelled or forfeited (in shares)				(3,964)
Unvested at the end of the period (in shares)			1,394,867	1,394,867
Shares reserved for future grants (all plans)			494,905	494,905
Weighted Average Grant Date Fair Value
Unvested at the beginning of the year (in dollars per share)				$ 86.40
Granted (in dollars per share)				82.81
Vested (in dollars per share)				84.54
Cancelled or forfeited (in dollars per share)				85.79
Unvested at the end of the period (in dollars per share)			$ 85.01	$ 85.01