Shareholders' Equity - Schedule of Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019
Equity, Class of Treasury Stock [Line Items]
Shares Acquired (in shares)					24.9
Average Cost per Share (USD per share)					$ 64.30
Total Acquired					$ 1,600
2018 Program
Equity, Class of Treasury Stock [Line Items]
Shares Acquired (in shares)					8.8
Average Cost per Share (USD per share)					$ 67.97
Total Acquired			$ 300	$ 300	$ 600
2019 Program
Equity, Class of Treasury Stock [Line Items]
Shares Acquired (in shares)					16.1
Average Cost per Share (USD per share)					$ 62.28
Total Acquired	$ 500	$ 500			$ 1,000