Background and Basis of Presentation (Share Repurchase Table) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Total number of shares repurchased (shares)	2.7	8.0
Aggregate cost of shares repurchased	$ 151	$ 513
Average price per share of shares repurchased (usd per share)	$ 56.34	$ 64.33

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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