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]	Noncontrolling Interest [Member]
Total Equity, beginning of period at Dec. 31, 2014	$ 10,789	$ 10,774	$ 74	$ 2,769	$ (936)	$ 10,289	$ (1,422)	$ 15
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	143	143		80		(241)	304
Other comprehensive income (loss)	(280)	(279)			(279)			(1)
Net income (loss)	1,661	1,668				1,668		(7)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(518)	(518)					(518)
Other transactions impacting noncontrolling interest	2	(4)		(4)				6
Total Equity, end of period at Sep. 30, 2015	11,787	11,774	74	2,845	(1,215)	11,706	(1,636)	13
Beginning Balance at Dec. 31, 2014	90
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(21)
Net income (loss)	(2)
Other transactions impacting noncontrolling interest
Ending Balance at Sep. 30, 2015	67
Total Equity, beginning of period at Jun. 30, 2015	11,303	11,290	74	2,835	(1,125)	11,178	(1,672)	13
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	28	28		11		(19)	36
Other comprehensive income (loss)	(91)	(90)			(90)			(1)
Net income (loss)	545	547				547		(2)
Other transactions impacting noncontrolling interest	2	(1)		(1)				3
Total Equity, end of period at Sep. 30, 2015	11,787	11,774	74	2,845	(1,215)	11,706	(1,636)	13
Beginning Balance at Jun. 30, 2015	76
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(9)
Net income (loss)	(1)
Other transactions impacting noncontrolling interest	1
Ending Balance at Sep. 30, 2015	67
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 Interest [Roll Forward]
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 Interest [Roll Forward]
Other comprehensive income (loss)	(3)
Net income (loss)	(1)
Other transactions impacting noncontrolling interest	1
Ending Balance at Sep. 30, 2016	$ 68