Common Stock (Earnings Per Share Data)(Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent									$ 2,571	$ 2,645	$ 2,533
Weighted Average Shares, Basic									691	694	707
Weighted Average Shares, Diluted									691	694	707
EPS, basic (usd per share)	$ 0.53	$ 1.44	$ 0.90	$ 0.83	$ 0.62	$ 1.29	$ 0.83	$ 1.06	$ 3.71	$ 3.80	$ 3.58
EPS, diluted (usd per share)	$ 0.53	$ 1.44	$ 0.90	$ 0.83	$ 0.62	$ 1.29	$ 0.83	$ 1.06	$ 3.71	$ 3.80	$ 3.58
Common Class A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent									$ 2,567	$ 2,640	$ 2,529
Weighted Average Shares, Basic									691	694	707
Weighted Average Shares, Diluted									691	694	707
EPS, basic (usd per share)									$ 3.71	$ 3.80	$ 3.58
EPS, diluted (usd per share)									$ 3.71	$ 3.80	$ 3.58
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)									$ 3.36	$ 3.24	$ 3.15