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		194	194		40		(226)	380
Other comprehensive income (loss)		258	258			258
Net income (loss)		1,966	1,971				1,971		(5)
Common dividends declared (per share: $0.04)		(10)	(10)				(10)
Repurchase of common stock		(1,988)	(1,988)					(1,988)
Other transactions impacting noncontrolling interest		(2)	(3)		(3)				1
Total Equity, end of period at Sep. 30, 2017		14,121	14,121	74	2,929	(1,124)	15,566	(3,324)	0
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)		(1)
Other transactions impacting noncontrolling interest		(5)
Ending Balance at Sep. 30, 2017		52
Total Equity, beginning of period (Previously Reported [Member]) at Jun. 30, 2017		14,547	14,546	74	2,922	(1,146)	15,102	(2,406)	1
Total Equity, beginning of period (Restatement Adjustment [Member])	[1]	(24)	(24)				(24)
Total Equity, beginning of period at Jun. 30, 2017		14,523	14,522	74	2,922	(1,146)	15,078	(2,406)	1
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans		63	63		7		(72)	128
Other comprehensive income (loss)		22	22			22
Net income (loss)		560	560				560
Repurchase of common stock		(1,046)	(1,046)					(1,046)
Other transactions impacting noncontrolling interest		(1)	0						(1)
Total Equity, end of period at Sep. 30, 2017		14,121	14,121	74	2,929	(1,124)	15,566	(3,324)	0
Beginning Balance (Previously Reported [Member]) at Jun. 30, 2017		58
Beginning Balance at Jun. 30, 2017		58
Redeemable Noncontrolling Interests
Net income (loss)		2
Other transactions impacting noncontrolling interest		(8)
Ending Balance at Sep. 30, 2017		52
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		114	114		45		(106)	175
Other comprehensive income (loss)		(536)	(536)			(536)
Net income (loss)		2,493	2,493				2,493
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 Sep. 30, 2018		15,555	15,555	74	2,985	(1,857)	18,474	(4,121)	0
Beginning Balance at Dec. 31, 2017		49
Redeemable Noncontrolling Interests
Other comprehensive income (loss)		(19)
Net income (loss)		6
Other transactions impacting noncontrolling interest		(6)
Ending Balance at Sep. 30, 2018		30
Total Equity, beginning of period at Jun. 30, 2018	[1]	14,743	14,743	74	2,974	(1,843)	17,722	(4,184)	0
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans		54	54		11		(20)	63
Other comprehensive income (loss)		(14)	(14)			(14)
Net income (loss)		772	772				772
Other transactions impacting noncontrolling interest		0	0
Total Equity, end of period at Sep. 30, 2018		15,555	$ 15,555	$ 74	$ 2,985	$ (1,857)	$ 18,474	$ (4,121)	$ 0
Beginning Balance at Jun. 30, 2018	[1]	39
Redeemable Noncontrolling Interests
Other comprehensive income (loss)		(9)
Net income (loss)		2
Other transactions impacting noncontrolling interest		(2)
Ending Balance at Sep. 30, 2018		$ 30

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