Share-Based Compensation Plans - Status of Stock Options and Changes (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SHARES
Granted (in shares)	0
Exercised (in shares)	(575,662)	(1,997,362)	(4,156,728)
Stock options under the Plan, the 2002 Plan, and the 1992 Plan
SHARES
Options Outstanding, at beginning of the year (in shares)	3,073,098
Granted (in shares)	0
Exercised (in shares)	(575,662)
Forfeited, Expired or Cancelled (in shares)	(16,375)
Options Outstanding, at the end of year (in shares)	2,481,061	3,073,098
Options Exercisable at the end of year (in shares)	1,723,323
Weighted average exercise price per share
Options Outstanding, Beginning Balance (in dollars per share)	$ 60.99
Granted (in dollars per share)	0.00
Exercised (in dollars per share)	56.55
Forfeited, Expired or Cancelled (in dollars per share)	79.78
Options Outstanding, Ending Balance (in dollars per share)	61.90	$ 60.99
Options Exercisable, at the end of the year (in dollars per share)	$ 56.82
Weighted average remaining contractual term (years)
Options Outstanding, at the end of the year	5 years 1 month
Options Exercisable, at the end of the year	4 years 2 months
Aggregate intrinsic value
Options Outstanding, at the end of year	$ 55.8
Options Exercisable at end of the year	$ 46.6