Common Stock (Earnings Per Share Data)(Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Common Stock [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	$ 691	$ 773
Average shares, basic	689	708
Average shares, diluted	689	708
EPS, basic (usd per share)	$ 1.00	$ 1.09
EPS, diluted (usd per share)	$ 1.00	$ 1.09
Common Class A [Member]
Common Stock [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	$ 691	$ 772
Average shares, basic	689	708
Average shares, diluted	689	708
EPS, basic (usd per share)	$ 1.00	$ 1.09
EPS, diluted (usd per share)	$ 1.00	$ 1.09
Number of stock options and performance and unvested stock awards excluded from the dilutive securities calculation	2	2
Dividends declared per share (usd per share)	$ 0.825	$ 0.795

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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