Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018	Jan. 01, 2019	Dec. 31, 2018	[1]	Mar. 31, 2018
Common Stock [Abstract]
Equity, Beginning Balance	$ 48,575.0		$ 47,035.0	$ 47,770.0
Net income	1,374.0		1,356.0	2,645.0		$ 2,595.0
Other comprehensive income (loss), net of tax	636.0		(241.0)	1,356.0		(798.0)
Dividends, Cash [Abstract]
Common	(432.0)		(355.0)	(868.0)		(713.0)
Preferred	(55.0)		(55.0)	(118.0)		(118.0)
Common Stock Activity, Net	10.0		9.0	10.0		9.0
Treasury stock activity	(782.0)		(814.0)	(1,403.0)		(1,439.0)
Other	55.0		40.0	(73.0)		(130.0)
Equity, Ending Balance	49,381.0		46,975.0	49,381.0		46,975.0
Preferred stock (less than)	$ 0.5	[1]	$ 0.5	$ 0.5	[1]	$ 0.5		$ 0.5		$ 0.5
Accounting Standards Update 2016-02 [Member]
Equity [Line Items]
Cumulative effect of new accounting principle in period of adoption							$ 62.0
Common Stock, par value $5.00
Common Stock [Abstract]
Beginning Balance (in shares)	452		470	457
Treasury stock activity, shares	(5)		(5)	(10)		(8)
Ending Balance, (in shares)	447		465	447		465
Equity, Beginning Balance	$ 2,711.0		$ 2,710.0	$ 2,711.0
Dividends, Cash [Abstract]
Equity, Ending Balance	2,711.0		2,710.0	2,711.0		$ 2,710.0
Capital Surplus - Preferred Stock [Member]
Common Stock [Abstract]
Equity, Beginning Balance	3,990.0		3,986.0	3,986.0
Dividends, Cash [Abstract]
Preferred stock discount accretion	1.0		1.0	2.0		2.0
Other				3.0
Equity, Ending Balance	3,991.0		3,987.0	3,991.0		3,987.0
Capital Surplus - Common Stock and Other [Member]
Common Stock [Abstract]
Equity, Beginning Balance	12,183.0		12,241.0	12,291.0
Dividends, Cash [Abstract]
Common Stock Activity, Net	10.0		9.0	10.0		9.0
Treasury stock activity	(1.0)		(32.0)	9.0		(26.0)
Other	65.0		45.0	(53.0)		(109.0)
Equity, Ending Balance	12,257.0		12,263.0	12,257.0		12,263.0
Retained Earnings [Member]
Common Stock [Abstract]
Equity, Beginning Balance	39,742.0		36,266.0	38,919.0
Net income	1,362.0		1,346.0	2,623.0		2,575.0
Dividends, Cash [Abstract]
Common	(432.0)		(355.0)	(868.0)		(713.0)
Preferred	(55.0)		(55.0)	(118.0)		(118.0)
Preferred stock discount accretion	(1.0)		(1.0)	(2.0)		(2.0)
Equity, Ending Balance	40,616.0		37,201.0	40,616.0		37,201.0
Retained Earnings [Member] | Accounting Standards Update 2016-02 [Member]
Equity [Line Items]
Cumulative effect of new accounting principle in period of adoption							$ 62.0
Accumulated Other Comprehensive Income (Loss) [Member]
Common Stock [Abstract]
Equity, Beginning Balance	(5.0)		(699.0)	(725.0)
Other comprehensive income (loss), net of tax	636.0		(241.0)	1,356.0		(798.0)
Dividends, Cash [Abstract]
Equity, Ending Balance	631.0		(940.0)	631.0		(940.0)
Treasury Stock [Member]
Common Stock [Abstract]
Equity, Beginning Balance	(10,085.0)		(7,535.0)	(9,454.0)
Dividends, Cash [Abstract]
Treasury stock activity	(781.0)		(782.0)	(1,412.0)		(1,413.0)
Equity, Ending Balance	(10,866.0)		(8,317.0)	(10,866.0)		(8,317.0)
Noncontrolling Interest [Member]
Common Stock [Abstract]
Equity, Beginning Balance	39.0		66.0	42.0
Net income	12.0		10.0	22.0		20.0
Dividends, Cash [Abstract]
Other	(10.0)		(5.0)	(23.0)		(21.0)
Equity, Ending Balance	$ 41.0		$ 71.0	$ 41.0		$ 71.0

[1] Par value less than $.5 million at each date.