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	90	90		49		(89)	130
Other comprehensive income (loss)	248	247			247			1
Net income (loss)	1,096	1,101				1,101		(5)
Common dividends declared (per share: $0.04)	(11)	(11)				(11)
Repurchase of common stock	(1,057)	(1,057)					(1,057)
Capital contribution by noncontrolling interest	5							5
Total Equity, end of period at Jun. 30, 2014	10,952	10,937	92	3,405	(273)	14,677	(6,964)	15
Beginning Balance at Dec. 31, 2013	$ 96
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)
Net income	$ 5
Capital contribution by noncontrolling interest	2
Distribution to noncontrolling interest	(4)
Ending Balance at Jun. 30, 2014	99
Total Equity, beginning of period at Mar. 31, 2014	10,569	10,556	92	3,392	(433)	14,136	(6,631)	13
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	62	62		13		(32)	81
Other comprehensive income (loss)	160	160			160
Net income (loss)	570	573				573		(3)
Repurchase of common stock	(414)	(414)					(414)
Capital contribution by noncontrolling interest	5							5
Total Equity, end of period at Jun. 30, 2014	10,952	10,937	92	3,405	(273)	14,677	(6,964)	15
Beginning Balance at Mar. 31, 2014	96
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	3
Net income	2
Capital contribution by noncontrolling interest	2
Distribution to noncontrolling interest	(4)
Ending Balance at Jun. 30, 2014	99
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	115	115		69		(222)	268
Other comprehensive income (loss)	(189)	(189)			(189)
Net income (loss)	1,116	1,121				1,121		(5)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(518)	(518)					(518)
Other transactions impacting noncontrolling interest	0	(3)		(3)				3
Total Equity, end of period at Jun. 30, 2015	11,303	11,290	74	2,835	(1,125)	11,178	(1,672)	13
Beginning Balance at Dec. 31, 2014	90
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(12)
Net income	(1)
Other transactions impacting noncontrolling interest	(1)
Ending Balance at Jun. 30, 2015	76
Total Equity, beginning of period at Mar. 31, 2015	10,958	10,942	74	2,823	(934)	10,635	(1,656)	16
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	53	53		14		(45)	84
Other comprehensive income (loss)	(191)	(191)			(191)
Net income (loss)	585	588				588		(3)
Repurchase of common stock	(100)	(100)					(100)
Other transactions impacting noncontrolling interest	(2)	(2)		(2)				0
Total Equity, end of period at Jun. 30, 2015	11,303	$ 11,290	$ 74	$ 2,835	$ (1,125)	$ 11,178	$ (1,672)	$ 13
Beginning Balance at Mar. 31, 2015	83
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(3)
Net income	(1)
Other transactions impacting noncontrolling interest	(3)
Ending Balance at Jun. 30, 2015	$ 76