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, 2012	$ 9,769	$ 9,769	$ 92	$ 3,295	$ (671)	$ 12,330	$ (5,277)	$ 0
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	185	185		61		(119)	243
Effects of acquisition of joint venture	14							14
Other comprehensive income (loss)	151	151			151
Net income (loss)	1,476	1,476				1,476
Common dividends declared (per share: $0.04)	(11)	(11)				(11)
Repurchase of common stock	(1,003)	(1,003)					(1,003)
Other transactions impacting noncontrolling interest	0	0
Total Equity, end of period at Dec. 31, 2013	10,581	10,567	92	3,356	(520)	13,676	(6,037)	14
Beginning Balance at Dec. 31, 2012	114
Redeemable Noncontrolling Interest [Roll Forward]
Effects of acquisition of joint venture	6
Other comprehensive income (loss)	(19)
Net income (loss)	2
Other transactions impacting noncontrolling interest	(7)
Ending Balance at Dec. 31, 2013	96
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	165	165		69		(124)	220
Other comprehensive income (loss)	(415)	(416)			(416)			1
Net income (loss)	2,093	2,102				2,102		(9)
Common dividends declared (per share: $0.04)	(11)	(11)				(11)
Repurchase of common stock	(1,629)	(1,629)					(1,629)
Retirement of treasury stock	0	0	(18)	(652)		(5,354)	6,024
Other transactions impacting noncontrolling interest	5	(4)		(4)				9
Total Equity, end of period at Dec. 31, 2014	10,789	10,774	74	2,769	(936)	10,289	(1,422)	15
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(7)
Net income (loss)	1
Other transactions impacting noncontrolling interest	0
Ending Balance at Dec. 31, 2014	90
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	183	183		99		(252)	336
Other comprehensive income (loss)	(315)	(314)			(314)			(1)
Net income (loss)	2,083	2,094				2,094		(11)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(683)	(683)					(683)
Other transactions impacting noncontrolling interest	(3)	(9)		(9)				6
Total Equity, end of period at Dec. 31, 2015	12,044	$ 12,035	$ 74	$ 2,859	$ (1,250)	$ 12,121	$ (1,769)	$ 9
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(17)
Net income (loss)	(6)
Other transactions impacting noncontrolling interest	2
Ending Balance at Dec. 31, 2015	$ 69