Equity - Stock Repurchases (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 04, 2013
Share repurchases
Total cash utilized		$ 1,240	$ 1,660	$ 1,001
Stock repurchased during period (shares)	400,000	5,900,000	8,400,000	6,800,000
2013 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program number of shares authorized to be repurchased (shares)					50,000,000
Maximum number of shares authorized for repurchase under stock repurchase plan as percentage of outstanding common stock (as a percent)					18.00%
Remaining shares available under repurchase program (shares)		4,700,000
Stock Repurchases
Share repurchases
Total number of shares purchased (shares)		1,200,000	900,000	3,500,000
Average price paid per share (USD per share)		$ 208.83	$ 182.93	$ 141.60
Total cash utilized		$ 240	$ 160	$ 501