Share Repurchase Programs and Dividends - Share Repurchase Programs (Details)	12 Months Ended			54 Months Ended	65 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2018 program	Dec. 31, 2019 USD ($) $ / shares shares	Apr. 30, 2018 USD ($)
Equity, Class of Treasury Stock [Line Items]
Stock repurchase programs, authorized amount	$ 13,000,000,000.0				$ 13,000,000,000.0
Number of share repurchase programs authorized | program				7
Stock repurchased (in shares) | shares	34,090,566	16,606,157	33,953,127
Aggregate stock repurchase price	$ 1,096,000,000	$ 799,000,000	$ 1,563,000,000
Share Repurchase Program April 2018 [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase programs, authorized amount						$ 2,000,000,000.0
Stock repurchase programs, remaining authorized amount	$ 565,000,000				$ 565,000,000
Stock repurchased (in shares) | shares	33,800,000	16,600,000	33,900,000		312,700,000
Aggregate stock repurchase price	$ 1,100,000,000	$ 800,000,000	$ 1,600,000,000		$ 12,400,000,000
Average cost per share (in dollars per share) | $ / shares	$ 32.09	$ 48.15	$ 45.68		$ 39.76