Shareholders' Equity Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Class of Stock [Line Items]
Repurchase and retirement of common stock		$ 111.4	$ 172.3	$ 410.5
Number of shares authorized to be repurchased (in shares)	681.7		681.7
Cash dividend paid during period, per share (in dollars per share)	$ 0.64	$ 0.63	$ 1.28	$ 1.26
Common stock excluded from calculation of diluted earnings per share (shares)		0.6	1.6	0.8
Common Stock
Class of Stock [Line Items]
Repurchase and retirement of common stock (shares)		0.8	1.5	3.3