Statement 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, 2015	$ 12,044	$ 12,035	$ 74	$ 2,859	$ (1,250)	$ 12,121	$ (1,769)	$ 9
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	52	52		38		(109)	123
Other comprehensive income (loss)	535	535			535
Net income (loss)	1,473	1,485				1,485		(12)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(110)	(110)					(110)
Other transactions impacting noncontrolling interest	(2)	(13)		(13)				11
Total Equity, end of period at Sep. 30, 2016	13,982	13,974	74	2,884	(715)	13,487	(1,756)	8
Beginning Balance at Dec. 31, 2015	69
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	(1)
Net income (loss)	(4)
Other transactions impacting noncontrolling interest	4
Ending Balance at Sep. 30, 2016	68
Total Equity, beginning of period at Jun. 30, 2016	13,364	13,356	74	2,879	(844)	13,046	(1,799)	8
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	35	35		7		(15)	43
Other comprehensive income (loss)	129	129			129
Net income (loss)	453	456				456		(3)
Other transactions impacting noncontrolling interest	1	(2)		(2)				3
Total Equity, end of period at Sep. 30, 2016	13,982	13,974	74	2,884	(715)	13,487	(1,756)	8
Beginning Balance at Jun. 30, 2016	71
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	(3)
Net income (loss)	(1)
Other transactions impacting noncontrolling interest	1
Ending Balance at Sep. 30, 2016	68
Total Equity, beginning of period at Dec. 31, 2016	13,727	13,723	74	2,892	(1,382)	13,855	(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	14,145	14,145	74	2,929	(1,124)	15,590	(3,324)	0
Beginning Balance at Dec. 31, 2016	58
Redeemable Noncontrolling Interests
Net income (loss)	(1)
Other transactions impacting noncontrolling interest	(5)
Ending Balance at Sep. 30, 2017	52
Total Equity, beginning of period at Jun. 30, 2017	14,547	14,546	74	2,922	(1,146)	15,102	(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	14,145	$ 14,145	$ 74	$ 2,929	$ (1,124)	$ 15,590	$ (3,324)	$ 0
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