Shareholders' Equity Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Class of Stock [Line Items]
Repurchase and retirement of common stock	$ 172.3	$ 299.1
Number of shares authorized to be repurchased (in shares)	681.7
Cash dividend paid during period, per share (in dollars per share)	$ 0.64	$ 0.63
Common stock excluded from calculation of diluted earnings per share (shares)	1.3	1.0
Common Stock
Class of Stock [Line Items]
Repurchase and retirement of common stock (shares)	1.5	2.5

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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