Equity Activity - AOCI Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	$ 16,929	$ 17,725
Other comprehensive income/(loss)	308	430
Balance at the End of the Period	16,607	18,290
Accumulated Other Comprehensive Income/(Loss)
Accumulated Other Comprehensive Income (Loss) (net of tax)
Balance at the Beginning of the Period	(29,490)	(26,592)
Other comprehensive income before reclassifications	(99)	(65)
Amount reclassified from accumulated other comprehensive income	407	495
Other comprehensive income/(loss)	308	430
Balance at the End of the Period	(29,182)	(28,583)
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		(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	(268)	51
Amount reclassified from accumulated other comprehensive income	75	(41)
Other comprehensive income/(loss)	(193)	10
Balance at the End of the Period	90	50
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	172	(115)
Amount reclassified from accumulated other comprehensive income		0
Other comprehensive income/(loss)	172	(115)
Balance at the End of the Period	(3,519)	(2,903)
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	(2)	0
Amount reclassified from accumulated other comprehensive income	333	537
Other comprehensive income/(loss)	330	537
Balance at the End of the Period	(25,753)	(25,730)
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	(1)	(2)
Amount reclassified from accumulated other comprehensive income		0
Other comprehensive income/(loss)	(1)	(2)
Balance at the End of the Period	$ (1)	(1)
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)