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, 2013	$ 10,581	$ 10,567	$ 92	$ 3,356	$ (520)	$ 13,676	$ (6,037)	$ 14
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	125	125		57		(104)	172
Other comprehensive income (loss)	102	101			101			1
Net income (loss)	1,629	1,635				1,635		(6)
Common dividends declared (per share: $0.04)	(11)	(11)				(11)
Repurchase of common stock	(1,256)	(1,256)					(1,256)
Other transactions impacting noncontrolling interest	5	(4)		(4)				9
Total Equity, end of period at Sep. 30, 2014	11,175	11,157	92	3,409	(419)	15,196	(7,121)	18
Beginning Balance at Dec. 31, 2013	96
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(6)
Net income (loss)	3
Other transactions impacting noncontrolling interest	0
Ending Balance at Sep. 30, 2014	93
Total Equity, beginning of period at Jun. 30, 2014	10,952	10,937	92	3,405	(273)	14,677	(6,964)	15
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	35	35		8		(15)	42
Other comprehensive income (loss)	(146)	(146)			(146)
Net income (loss)	533	534				534		(1)
Repurchase of common stock	(199)	(199)					(199)
Other transactions impacting noncontrolling interest	0	(4)		(4)				4
Total Equity, end of period at Sep. 30, 2014	11,175	11,157	92	3,409	(419)	15,196	(7,121)	18
Beginning Balance at Jun. 30, 2014	99
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(6)
Net income (loss)	(2)
Other transactions impacting noncontrolling interest	2
Ending Balance at Sep. 30, 2014	93
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