Share-Based Compensation Plans - Status of Stock Options and Changes (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
SHARES
Options Outstanding, at beginning of the year (in shares)	213,182
Granted (in shares)	0
Exercised (in shares)	(90,295)	(154,476)	(42,143)
Forfeited, Expired or Cancelled (in shares)	0
Options Outstanding, at the end of year (in shares)	122,887	213,182
Options Exercisable at the end of year (in shares)	122,887
WEIGHTED AVERAGE EXERCISE PRICE PER SHARE
Options Outstanding, Beginning Balance (in dollars per share)	$ 74.36
Granted (in dollars per share)	0
Exercised (in dollars per share)	71.14
Forfeited, Expired or Cancelled (in dollars per share)	0
Options Outstanding, Ending Balance (in dollars per share)	76.72	$ 74.36
Options Exercisable, at the end of the year (in dollars per share)	$ 76.72
WEIGHTED AVERAGE REMAINING CONTRACTUAL TERM (YEARS)
Options Outstanding, at the end of the year	9 months 18 days
Options Exercisable, at the end of the year	9 months 18 days
AGGREGATE INTRINSIC VALUE
Options Outstanding, at the end of year	$ 7.4
Options Exercisable at end of the year	$ 7.4