Stock-Based Compensation and Other Stock Plans - Summary of Stock Option Activity and Stock-settled SARs (Detail) $ / shares in Units, shares in Thousands, $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Stock Option
Shares (in thousands)
Beginning balance (in shares) | shares	3,198
Granted (in shares) | shares	515
Exercised (in shares) | shares	(244)
Forfeited or expired (in shares) | shares	(34)
Ending balance (in shares) | shares	3,435
Exercisable at June 30, 2018 (in shares) | shares	2,340
Exercise Price Per Share
Beginning balance (in dollars per share) | $ / shares	$ 115.30
Granted (in dollars per share) | $ / shares	161.18
Exercised (in dollars per share) | $ / shares	73.33
Forfeited or expired (in dollars per share) | $ / shares	159.17
Ending balance (in dollars per share) | $ / shares	124.72
Exercisable at June 30, 2018 (in dollars per share) | $ / shares	$ 108.26
Additional Disclosures
Outstanding, remaining contractual term (in years)	6 years 7 months 6 days
Exercisable, remaining contractual term (in years)	5 years 6 months
Outstanding, aggregate intrinsic value | $	$ 128.8
Exercisable, aggregate intrinsic value | $	$ 124.4
Stock-Settled SARs
Stock-settled SARs (in thousands)
Beginning balance (in shares) | shares	360
Granted (in shares) | shares	89
Exercised (in shares) | shares	(8)
Forfeited or expired (in shares) | shares	(21)
Ending balance (in shares) | shares	420
Exercisable at June 30, 2018 (in shares) | shares	238
Exercise Price Per Share
Beginning balance (in dollars per share) | $ / shares	$ 138.63
Granted (in dollars per share) | $ / shares	161.18
Exercised (in dollars per share) | $ / shares	101.87
Forfeited or expired (in dollars per share) | $ / shares	131.42
Ending balance (in dollars per share) | $ / shares	144.43
Exercisable at June 30, 2018 (in dollars per share) | $ / shares	$ 132.55
Additional Disclosures
Outstanding, remaining contractual term	7 years 8 months 12 days
Exercisable, remaining contractual term	6 years 8 months 12 days
Outstanding, aggregate intrinsic value | $	$ 7.7
Exercisable, aggregate intrinsic value | $	$ 7.0