Shareholders' Equity - Repurchases (Details) - USD ($) shares in Millions	1 Months Ended		12 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Aug. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Stock repurchased during the period (in shares)			55.4
Stock repurchased during the period			$ 4,400,000,000
2016 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Authorized				$ 15,000,000,000.0
Remaing as of December 31, 2019				13,900,000,000
2014 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Authorized				10,000,000,000.0
Remaing as of December 31, 2019				$ 0
Accelerated share repurchases agreement amount		$ 3,600,000,000			$ 3,600,000,000
Accelerated share repurchases percent of notional amount received in shares		80.00%
Number of shares purchased (in shares)		36.1
Amount of repurchases under the program		$ 2,900,000,000
Accelerated share repurchases, maximum number of shares (in shares)	9.9
Accelerated share repurchases, percent of notional amount in shares to be received at end of program	20.00%
Foreign Exchange Forward | 2014 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Derivative notional amount		$ 700,000,000