Common Stock (Earnings Per Share Data)(Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Excluding Participating Securities									$ 3,059	$ 2,567	$ 2,640
Weighted Average Number of Shares Outstanding, Basic									700	691	694
Weighted Average Number of Shares Outstanding, Diluted									700	691	694
EPS, basic (usd per share)	$ 1.00	$ 1.36	$ 0.98	$ 1.02	$ 0.53	$ 1.44	$ 0.90	$ 0.83	$ 4.37	$ 3.71	$ 3.80
EPS, diluted (usd per share)	$ 1.00	$ 1.36	$ 0.98	$ 1.02	$ 0.53	$ 1.44	$ 0.90	$ 0.83	$ 4.37	$ 3.71	$ 3.80
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									2	2	2
Dividends declared per share (usd per share)									$ 3.49	$ 3.36	$ 3.24