Stock-based Compensation Plans - Summary of Stock Option Activity (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning balance, shares	38,583	41,939	42,059
Granted, shares	7,118	6,105	6,570
Exercised, shares	(2,561)	(8,269)	(5,168)
Forfeited, shares	(2,053)	(1,192)	(1,522)
Ending balance, shares	41,087	38,583	41,939
Beginning balance, Weighted-average exercise price	$ 76.10	$ 70.33	$ 67.77
Granted, Weighted-average exercise price	86.86	99.04	72.16
Exercised, Weighted-average exercise price	60.10	64.19	51.73
Forfeited, Weighted-average exercise price	80.34	73.56	70.57
Ending balance, Weighted-average exercise price	$ 78.73	$ 76.10	$ 70.33