Earnings Per Share - Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Shares repurchased (in shares)	1	16	10	39
Cost of shares	$ 48	$ 1,111	$ 664	$ 2,767	[1]

[1] Certain prior year data has been reclassified to conform to the current presentation.