Share-Based Compensation - Activity Related to Stock Options (Detail) - Stock Option Awards - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Number of shares
Balance at beginning of the period (in shares)	686,366,000	721,538,000
Granted (in shares)	92,162,000	70,433,000
Exercised (in shares)	(21,212,000)	(24,457,000)
Forfeited or expired (in shares)	(14,513,000)	(12,539,000)
Balance at end of the period (in shares)	742,803,000	754,975,000
Exercisable at period end (in shares)	519,496,000	509,347,000
Weighted Average Exercise Price
Balance at beginning of the period (in usd per share)	$ 58.24	$ 55.38
Granted (in usd per share)	82.20	85.52
Exercised (in usd per share)	52.10	53.85
Forfeited or expired (in usd per share)	65.27	75.77
Balance at end of the period (in usd per share)	61.25	57.90
Exercisable at period end (in usd per share)	$ 56.53	$ 55.78