Earnings Per Share - Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Shares repurchased (in shares)	1	11	10	23
Cost of shares	$ 39	$ 860	$ 616	$ 1,656	[1]

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