Statement of Changes in Total Equity (USD $) In Millions, unless otherwise specified	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]
Beginning Balance at Mar. 31, 2013	$ 113
Total Equity, beginning of period at Mar. 31, 2013	9,660	9,660	92	3,305	(756)	12,328	(5,309)
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	75	75		21		(27)	81
Other comprehensive income (loss)	(258)	(258)			(258)
Net income	505	505				505
Repurchase of common stock	(207)	(207)					(207)
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(6)
Net income	1
Distribution to noncontrolling interest	(7)
Ending Balance at Jun. 30, 2013	101
Total Equity, end of period at Jun. 30, 2013	9,775	9,775	92	3,326	(1,014)	12,806	(5,435)	0
Beginning Balance at Dec. 31, 2012	114
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	102	102		31		(75)	146
Other comprehensive income (loss)	(343)	(343)			(343)
Net income	562	562				562
Common dividends declared (per share: $0.04)	(11)	(11)				(11)
Repurchase of common stock	(304)	(304)					(304)
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(9)
Net income	3
Distribution to noncontrolling interest	(7)
Ending Balance at Jun. 30, 2013	101
Total Equity, end of period at Jun. 30, 2013	9,775	9,775	92	3,326	(1,014)	12,806	(5,435)	0
Beginning Balance at Dec. 31, 2013	96
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	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
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	0
Net income	5
Capital contribution by noncontrolling interest	2
Distribution to noncontrolling interest	(4)
Ending Balance at Jun. 30, 2014	99
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
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	570	573				573		(3)
Repurchase of common stock	(414)	(414)					(414)
Capital contribution by noncontrolling interest	5							5
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, end of period at Jun. 30, 2014	$ 10,952	$ 10,937	$ 92	$ 3,405	$ (273)	$ 14,677	$ (6,964)	$ 15