Common Stock (Earnings Per Share Data)(Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Common Stock [Line Items]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 1,054	$ 937	$ 2,255	$ 2,310
Average shares, basic	689	688	689	696
Average shares, diluted	691	688	690	696
EPS, basic (usd per share)	$ 1.52	$ 1.36	$ 3.27	$ 3.31
EPS, diluted (usd per share)	$ 1.52	$ 1.36	$ 3.26	$ 3.31
Common Class A [Member]
Common Stock [Line Items]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 1,053	$ 935	$ 2,252	$ 2,307
Average shares, basic	689	688	689	696
Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements	2		1
Average shares, diluted	691	688	690	696
EPS, basic (usd per share)	$ 1.52	$ 1.36	$ 3.27	$ 3.31
EPS, diluted (usd per share)	$ 1.52	1.36	$ 3.26	$ 3.31
Number of stock options and performance and unvested stock awards excluded from the dilutive securities calculation	2		2	2
Dividends declared per share (usd per share)	$ 0.855	$ 0.825	$ 2.505	$ 2.42