Supplemental Equity and Comprehensive Income Information - SE Rf (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Increase (decrease) in equity
Balance at the beginning of the period	$ 10,428	$ 11,644	$ 11,622	$ 10,343
Net income	1,546	1,433	4,014	4,344
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	(112)	44	(441)	269
Defined benefit pension and postretirement plans adjustment	114	80	344	241
Cash flow hedging instruments unrealized gain (loss)	46	(49)	147	(176)
Total other comprehensive income (loss), net of tax	48	75	50	334
Dividends declared	(794)	(701)	(2,406)	(2,104)
Stock-based compensation	47	58	(245)	241
Reacquired stock	(1,058)	(394)	(3,621)	(1,547)
Issuances pursuant to stock option and benefit plans	94	87	407	591
Balance at the end of the period	10,311	12,202	10,311	12,202
Common Stock and Additional Paid-in Capital
Increase (decrease) in equity
Balance at the beginning of the period	5,559	5,253	5,361	5,070
Other comprehensive income (loss), net of tax:
Stock-based compensation	47	58	(245)	241
Balance at the end of the period	5,606	5,311	5,606	5,311
Retained Earnings
Increase (decrease) in equity
Balance at the beginning of the period	39,442	38,793	39,115	37,907
Net income	1,543	1,429	4,002	4,335
Other comprehensive income (loss), net of tax:
Dividends declared	(794)	(701)	(2,406)	(2,104)
Issuances pursuant to stock option and benefit plans	(71)	(67)	(591)	(684)
Balance at the end of the period	40,120	39,454	40,120	39,454
Treasury Stock
Increase (decrease) in equity
Balance at the beginning of the period	(27,617)	(25,466)	(25,887)	(25,434)
Other comprehensive income (loss), net of tax:
Reacquired stock	(1,058)	(394)	(3,621)	(1,547)
Issuances pursuant to stock option and benefit plans	165	154	998	1,275
Balance at the end of the period	(28,510)	(25,706)	(28,510)	(25,706)
Accumulated Other Comprehensive Income (Loss)
Increase (decrease) in equity
Balance at the beginning of the period	(7,019)	(6,989)	(7,026)	(7,245)
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	(109)	45	(433)	267
Defined benefit pension and postretirement plans adjustment	114	80	344	241
Cash flow hedging instruments unrealized gain (loss)	46	(49)	147	(176)
Balance at the end of the period	(6,968)	(6,913)	(6,968)	(6,913)
Noncontrolling Interest
Increase (decrease) in equity
Balance at the beginning of the period	63	53	59	45
Net income	3	4	12	9
Other comprehensive income (loss), net of tax:
Cumulative translation adjustment	(3)	(1)	(8)	2
Balance at the end of the period	$ 63	$ 56	$ 63	$ 56