Capital Stock - Additional Information (Details) - USD ($)		1 Months Ended	12 Months Ended			72 Months Ended
	Jan. 31, 2018	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Class of Stock [Line Items]
Common stock, shares authorized (in shares)			5,000,000,000	5,000,000,000		5,000,000,000
Preferred stock, shares issued (in shares)			0	0	0	0
Preferred stock, shares outstanding (in shares)			0	0	0	0
Amount of shares repurchased			$ 1,499,000,000	$ 1,994,000,000	$ 2,202,000,000
Class A Common Stock, no par value
Class of Stock [Line Items]
Common stock, shares authorized (in shares)			5,000,000,000.0
Preferred stock, shares authorized (in shares)			500,000,000
Common stock reserved for stock option and other stock awards (in shares)			96,000,000
Stock repurchase value				$ 13,700,000,000		$ 13,700,000,000
Amount of shares repurchased			$ 1,500,000,000
Number of shares repurchased (in shares)			30,902,465	47,258,884	50,598,902
Average cost of shares repurchased (in dollars per share)			$ 48.51
Stock repurchase remaining amount			$ 3,200,000,000
Class A Common Stock, no par value | Subsequent Event
Class of Stock [Line Items]
Amount of shares repurchased		$ 19,000,000
Class A Common Stock, no par value | Share Repurchase Program amended January 1, 2018
Class of Stock [Line Items]
Stock repurchase value	$ 19,700,000,000
Increase in share repurchase value	$ 6,000,000,000.0
Stock repurchase expiration date	Dec. 31, 2020
Common Stock | Prior to January 1, 2018
Class of Stock [Line Items]
Amount of shares repurchased						$ 15,000,000,000.0