Equity Activity - AOCI Rollforward (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period		$ 17,776	$ 18,648	$ 16,929	$ 17,725
Other comprehensive income/(loss)		(245)	470	404	1,194
Balance at the End of the Period		18,096	19,918	18,096	19,918
Common stock repurchase authorization available, value		2,008		2,008
Accumulated Other Comprehensive Income/(Loss)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period		(28,841)	(28,290)	(29,490)	(26,592)
Other comprehensive income before reclassifications				(916)	(695)
Amount reclassified from accumulated other comprehensive income				1,320	1,889
Other comprehensive income/(loss)		(245)	470	404	1,194
Balance at the End of the Period		(29,086)	(27,820)	(29,086)	(27,820)
Accumulated Other Comprehensive Income/(Loss) | Accounting Standards Updates 2016-01 (Financial Instruments), 2017-12 (Hedging) and 2018-02 (Stranded Tax Effects)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Cumulative Effect Of Prospective Application Of New Accounting Principle, Net Of Tax	[1]				(2,422)
Net Unrealized Gains/(Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period				284	35
Other comprehensive income before reclassifications		(329)	(35)	(601)	(95)
Amount reclassified from accumulated other comprehensive income				315	305
Other comprehensive income/(loss)		36	(14)	(287)	210
Balance at the End of the Period		(3)	250	(3)	250
Net Unrealized Gains/(Losses) on Cash Flow Hedges | Accounting Standards Updates 2016-01 (Financial Instruments), 2017-12 (Hedging) and 2018-02 (Stranded Tax Effects)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Cumulative Effect Of Prospective Application Of New Accounting Principle, Net Of Tax					5
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period				(3,690)	(2,834)
Other comprehensive income before reclassifications				(405)	(663)
Other comprehensive income/(loss)		(618)	(44)	(405)	(663)
Balance at the End of the Period		(4,095)	(3,451)	(4,095)	(3,451)
Foreign Currency Translation Adjustments | Accounting Standards Updates 2016-01 (Financial Instruments), 2017-12 (Hedging) and 2018-02 (Stranded Tax Effects)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Cumulative Effect Of Prospective Application Of New Accounting Principle, Net Of Tax					46
Net Change Retirement-Related Benefit Plans
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period				(26,083)	(23,796)
Other comprehensive income before reclassifications				89	65
Amount reclassified from accumulated other comprehensive income				1,005	1,584
Other comprehensive income/(loss)		335	527	1,095	1,648
Balance at the End of the Period		(24,988)	(24,618)	(24,988)	(24,618)
Net Change Retirement-Related Benefit Plans | Accounting Standards Updates 2016-01 (Financial Instruments), 2017-12 (Hedging) and 2018-02 (Stranded Tax Effects)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Cumulative Effect Of Prospective Application Of New Accounting Principle, Net Of Tax					(2,471)
Net Unrealized Gains/(Losses) on Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period				0	3
Other comprehensive income before reclassifications		2	0	1	(1)
Other comprehensive income/(loss)		2	0	1	(1)
Balance at the End of the Period		$ 0	$ 0	$ 0	0
Net Unrealized Gains/(Losses) on Available-For-Sale Securities | Accounting Standards Updates 2016-01 (Financial Instruments), 2017-12 (Hedging) and 2018-02 (Stranded Tax Effects)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Cumulative Effect Of Prospective Application Of New Accounting Principle, Net Of Tax					$ (2)

[1] * Reflects the adoption of the FASB guidance on stranded tax effects, hedging and financial instruments. Refer to note 2, “Accounting Changes.”