Earnings Per Share - Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Shares repurchased (in shares)	9	12
Cost of shares	$ 577	$ 796	[1]

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