Consolidated Statements of Changes in Total Equity - USD ($) $ in Millions	Total	Shareholders' Equity [Member]	Common Stock [Member]	Additional Paid In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Other noncontrolling interests [Member]
Total Equity, beginning of period at Dec. 31, 2017	$ 13,711	$ 13,711	$ 74	$ 2,940	$ (1,082)	$ 15,800	$ (4,021)	$ 0
Increase (Decrease) In Stockholders Equity [Roll Forward]
Reclassification adjustment related to U.S. tax reform legislation	0	0			(229)	229
Effect of issuing stock for employee benefit plans	60	60		34		(86)	112
Other comprehensive income (loss)	(522)	(522)			(522)
Net income (loss)	1,721	1,721				1,721
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(275)	(275)					(275)
Other transactions impacting noncontrolling interest	0	0
Total Equity, end of period at Jun. 30, 2018	14,743	14,743	74	2,974	(1,843)	17,722	(4,184)	0
Beginning Balance at Dec. 31, 2017	49
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	(10)
Net income (loss)	4
Other transactions impacting noncontrolling interest	(4)
Ending Balance at Jun. 30, 2018	39
Total Equity, beginning of period at Mar. 31, 2018	14,195	14,195	74	2,963	(1,547)	16,933	(4,228)	0
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	38	38		11		(17)	44
Other comprehensive income (loss)	(296)	(296)			(296)
Net income (loss)	806	806				806
Other transactions impacting noncontrolling interest	0	0
Total Equity, end of period at Jun. 30, 2018	14,743	14,743	74	2,974	(1,843)	17,722	(4,184)	0
Beginning Balance at Mar. 31, 2018	49
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	(8)
Net income (loss)	2
Other transactions impacting noncontrolling interest	(4)
Ending Balance at Jun. 30, 2018	39
Total Equity, beginning of period at Dec. 31, 2018	41,035	41,028	4	27,751	(1,711)	15,088	(104)	7
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	163	163		140			23
Other comprehensive income (loss)	746	746			746
Net income (loss)	2,777	2,776				2,776		1
Common dividends declared (per share: $0.04)	(15)	(15)				(15)
Repurchase of common stock	(868)	(868)					(868)
Other transactions impacting noncontrolling interest	(5)	0						(5)
Total Equity, end of period at Jun. 30, 2019	43,818	43,815	4	27,891	(965)	17,834	(949)	3
Beginning Balance at Dec. 31, 2018	37
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	(4)
Net income (loss)	5
Other transactions impacting noncontrolling interest	(7)
Ending Balance at Jun. 30, 2019	31
Total Equity, beginning of period at Mar. 31, 2019	42,413	42,408	4	27,855	(1,282)	16,426	(595)	5
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	88	88		36		0	52
Other comprehensive income (loss)	317	317			317
Net income (loss)	1,408	1,408				1,408
Repurchase of common stock	(406)	(406)					(406)
Other transactions impacting noncontrolling interest	(2)	0						(2)
Total Equity, end of period at Jun. 30, 2019	43,818	$ 43,815	$ 4	$ 27,891	$ (965)	$ 17,834	$ (949)	$ 3
Beginning Balance at Mar. 31, 2019	38
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	(2)
Net income (loss)	2
Other transactions impacting noncontrolling interest	(7)
Ending Balance at Jun. 30, 2019	$ 31