Equity - Share Repurchase Program (Details) - USD ($) shares in Millions, $ in Millions		12 Months Ended
	Dec. 13, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 15, 2018
Equity, Class of Treasury Stock [Line Items]
Payment for shares repurchased		$ 428	$ 12,215	$ 1,125
Remaining share repurchase authorization amount		$ 4,000
February 2017 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (in shares)		4
Payment for shares repurchased		$ 300
February 2018 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Amount authorized under stock repurchase program					$ 10,000
December 2018 Stock Repurchase Authorization
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (in shares)			109
Payment for shares repurchased			$ 10,700
Increase in authorized share repurchase amount	$ 5,000
Open Market Stock Repurchases
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (in shares)			11	13
Payment for shares repurchased			$ 1,300	$ 1,000