Common Stock (Earnings Per Share Data) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Excluding Participating Securities									$ 2,642	$ 3,059	$ 2,567
Weighted Average Number of Shares Outstanding, Basic									708	700	691
Weighted Average Number of Shares Outstanding, Diluted									708	700	691
EPS, basic (usd per share)	$ 0.62	$ 1.51	$ 0.72	$ 0.88	$ 1.00	$ 1.36	$ 0.98	$ 1.02	$ 3.73	$ 4.37	$ 3.71
EPS, diluted (usd per share)	$ 0.62	$ 1.51	$ 0.72	$ 0.88	$ 1.00	$ 1.36	$ 0.98	$ 1.02	$ 3.73	$ 4.37	$ 3.71
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									2	2	2
Dividends declared per share (usd per share)									$ 3.6350	$ 3.49	$ 3.36