Shareholders' Equity - Schedule of Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity, Class of Treasury Stock [Line Items]
Shares Acquired (in shares)		6.5
Average Cost per Share (USD per share)		$ 77.35
Total Acquired		$ 500
Cash dividends declared (in USD per share)		$ 2.08	$ 1.98	$ 1.78
Total (In millions)		$ 734	$ 728	$ 665
2019 Program
Equity, Class of Treasury Stock [Line Items]
Shares Acquired (in shares)		6.5
Average Cost per Share (USD per share)		$ 77.35
Total Acquired	$ 500	$ 500