Shareholders' Equity - Schedule of Stock Repurchases (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended		99 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020
Equity, Class of Treasury Stock [Line Items]
Total repurchase cost		$ 463	$ 1,056	$ 101
2012 - Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Shares purchased (in shares)	0.0		5.8		2.2	6.4	130.9
Average price per share (in dollars per share)	$ 0		$ 183.23		$ 212.78	$ 181.07
Total repurchase cost	$ 0		$ 1,050		$ 461	$ 1,150	$ 13,400
Additional associated costs	0		6		2	7
Total costs recorded to retained earnings	$ 0		$ 1,056		$ 463	$ 1,157