Capital Stock - Additional Information (Detail)	1 Months Ended	12 Months Ended
	May 31, 2016 $ / shares shares	Dec. 31, 2018 USD ($) $ / shares Directors shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Oct. 31, 2017 USD ($)	Nov. 30, 2016 USD ($)
Capital Structure [Line Items]
Common stock, shares authorized		1,800,000,000	1,800,000,000
Repurchase of common stock, shares		14,070,000	25,092,000	36,325,000
Repurchase price of common stock, per share | $ / shares		$ 108.74	$ 81.73	$ 75.72
Share repurchase program authorized amount | $			$ 2,000,000,000	$ 3,000,000,000	$ 2,000,000,000	$ 2,000,000,000
Share repurchase program, remaining authorized repurchase amount | $		$ 272,000,000	$ 1,802,000,000	$ 1,853,000,000	$ 2,000,000,000
Share Repurchase Program Two [Member]
Capital Structure [Line Items]
Repurchase of common stock, shares				26,964,000
Repurchase price of common stock, per share | $ / shares				$ 74.20
Kohlberg Kravis Roberts & Co [Member] | Share Repurchase Program One [Member]
Capital Structure [Line Items]
Repurchase of common stock, shares	9,361,000
Repurchase price of common stock, per share | $ / shares	$ 80.12
Percentage of discount on share repurchase	1.00%
Minimum [Member]
Capital Structure [Line Items]
Number of directors as per the amended and restated by-laws | Directors		3