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 (Previously Reported [Member]) at Dec. 31, 2016		$ 13,727	$ 13,723	$ 74	$ 2,892	$ (1,382)	$ 13,855	$ (1,716)	$ 4
Total Equity, beginning of period (Restatement Adjustment [Member])	[1]	(24)	(24)				(24)
Total Equity, beginning of period at Dec. 31, 2016		13,703	13,699	74	2,892	(1,382)	13,831	(1,716)	4
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans		131	131		33		(154)	252
Other comprehensive income (loss)		236	236			236
Net income (loss)		1,406	1,411				1,411		(5)
Common dividends declared (per share: $0.04)		(10)	(10)				(10)
Repurchase of common stock		(942)	(942)					(942)
Other transactions impacting noncontrolling interest		(1)	(3)		(3)				2
Total Equity, end of period at Jun. 30, 2017		14,523	14,522	74	2,922	(1,146)	15,078	(2,406)	1
Beginning Balance (Previously Reported [Member]) at Dec. 31, 2016		58
Beginning Balance at Dec. 31, 2016		58
Redeemable Noncontrolling Interests
Other comprehensive income (loss)		0
Net income (loss)		(3)
Other transactions impacting noncontrolling interest		3
Ending Balance at Jun. 30, 2017		58
Total Equity, beginning of period (Previously Reported [Member]) at Mar. 31, 2017		14,229	14,226	74	2,912	(1,252)	14,356	(1,864)	3
Total Equity, beginning of period (Restatement Adjustment [Member])	[1]	(24)	(24)				(24)
Total Equity, beginning of period at Mar. 31, 2017		14,205	14,202	74	2,912	(1,252)	14,332	(1,864)	3
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans		93	93		10		(67)	150
Other comprehensive income (loss)		106	106			106
Net income (loss)		811	813				813		(2)
Repurchase of common stock		(692)	(692)					(692)
Other transactions impacting noncontrolling interest		0	0
Total Equity, end of period at Jun. 30, 2017		14,523	14,522	74	2,922	(1,146)	15,078	(2,406)	1
Beginning Balance (Previously Reported [Member]) at Mar. 31, 2017		56
Beginning Balance at Mar. 31, 2017		56
Redeemable Noncontrolling Interests
Other comprehensive income (loss)		2
Net income (loss)		(1)
Other transactions impacting noncontrolling interest		1
Ending Balance at Jun. 30, 2017		58
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	[1]	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	[1]	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		0
Common dividends declared (per share: $0.04)		0	0
Repurchase of common stock		0	0					0
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	[1]	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

[1] See Note 2 for further information about adjustments resulting from the Company's adoption of new accounting standards in 2018.