Capital Stock - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares Directors shares	Dec. 31, 2019 $ / shares shares	Dec. 31, 2018 $ / shares shares	Feb. 01, 2021 USD ($)	Jan. 31, 2020 USD ($)	Jan. 31, 2019 USD ($)	Oct. 31, 2017 USD ($)
Capital Structure [Line Items]
Common stock, shares authorized | shares	1,800,000,000	1,800,000,000
Repurchase of common stock, shares | shares	3,287,000	7,949,000	14,070,000.000
Repurchase price of common stock, per share | $ / shares	$ 134.18	$ 129.71	$ 108.74
Share repurchase program authorized amount					$ 6,000,000,000	$ 6,000,000,000	$ 6,000,000,000
Share repurchase program, remaining authorized repurchase amount	$ 2,800,000,000				$ 2,000,000,000	$ 2,000,000,000	$ 2,000,000,000
Subsequent Event [Member]
Capital Structure [Line Items]
Share repurchase program authorized amount				$ 8,800,000,000
Share repurchase program, remaining authorized repurchase amount				2,800,000,000
Stock repurchase program additional authorized amount				$ 6,000,000,000
Minimum [Member]
Capital Structure [Line Items]
Number of directors as per the amended and restated by-laws | Directors	3