Capital Stock - Common Shares in Treasury and Common Shares Outstanding (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reconciliation Of Common Stock And Treasury Stock Balances [Roll Forward]
Beginning balance outstanding (in shares)	261,100,000	268,700,000
Treasury stock sold (in shares)	(75,000)
Ending balance outstanding (in shares)	258,900,000	261,100,000	268,700,000
Proceeds from treasury stock issued	$ 22.0	$ 11.7	$ 182.4
Shares in Treasury
Reconciliation Of Common Stock And Treasury Stock Balances [Roll Forward]
Beginning balance in treasury (in shares)	11,313,634	1,138,692	81,866,907
Shares tendered as payment for option rights exercised (in shares)	3,861	4,324	10,140
Shares tendered in connection with vesting of restricted stock units (in shares)	124,852	95,618	133,077
Treasury stock purchased (in shares)	(3,350,000)	(10,075,000)	(11,700,000)
Treasury stock, retired (in shares)			(91,746,432)
Treasury stock sold (in shares)			(825,000)
Ending balance in treasury (in shares)	14,717,347	11,313,634	1,138,692
Shares Outstanding
Reconciliation Of Common Stock And Treasury Stock Balances [Roll Forward]
Beginning balance outstanding (in shares)	261,143,805	268,676,631	276,434,517
Shares issued for exercise of option rights (in shares)	778,075	2,365,168	2,873,646
Shares tendered as payment for option rights exercised (in shares)	(3,861)	(4,324)	(10,140)
Shares issued for vesting of restricted stock units (in shares)	357,832	276,948	386,685
Shares tendered in connection with vesting of restricted stock units (in shares)	(124,852)	(95,618)	(133,077)
Treasury stock purchased (in shares)	(3,350,000)	(10,075,000)	(11,700,000)
Treasury stock sold (in shares)			(825,000)
Ending balance outstanding (in shares)	258,875,999	261,143,805	268,676,631