Common Stock (Earnings Per Share Data)(Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Common Stock [Line Items]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 510	$ 600	$ 1,201	$ 1,373
Average shares, basic	689	692	689	700
Average shares, diluted	690	692	689	700
EPS, basic (usd per share)	$ 0.74	$ 0.87	$ 1.74	$ 1.96
EPS, diluted (usd per share)	$ 0.74	$ 0.87	$ 1.74	$ 1.96
Common Class A [Member]
Common Stock [Line Items]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 508	$ 600	$ 1,199	$ 1,372
Average shares, basic	689	692	689	700
Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements	1
Average shares, diluted	690	692	689	700
EPS, basic (usd per share)	$ 0.74	$ 0.87	$ 1.74	$ 1.96
EPS, diluted (usd per share)	$ 0.74	$ 0.87	$ 1.74	$ 1.96
Number of stock options and performance and unvested stock awards excluded from the dilutive securities calculation	2	2	2	2
Dividends declared per share (usd per share)	$ 0.825	$ 0.795	$ 1.65	$ 1.59

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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