Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Stock Repurchase Program, Authorized Amount	$ 400
Treasury Stock, Value, Acquired, Cost Method	163	$ 101	$ 300
Proceeds from Issuance of Common Stock	$ 481	$ 0	$ 0
Stock Issued During Period, Shares, New Issues	6,172,840
Shares Issued, Price Per Share	$ 81.00
Common stock par value	$ 0.01
Common Stock Issued Underwriter Option	925,926
Common Stock Price Per Share Underwriter Option	$ 81.00