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]
Total Equity, beginning of period at Mar. 31, 2012		$ 8,561	$ 92	$ 3,268	$ (722)	$ 11,123	$ (5,200)
Effect of issuing stock for employee benefit plans, Additional Paid In Capital				8
Effect of issuing stock for employee benefit plans, Retained Earnings						(2)
Effect of issuing stock for employee benefit plans, Treasury Stock							24
Effect of issuing stock for employee benefit plans, Total Equity		30
Other comprehensive income (loss) attributable to Parent	51	51			51
Shareholders' net income	380	380				380
Net income	380
Total Equity, end of period at Jun. 30, 2012		9,022	92	3,276	(671)	11,501	(5,176)
Total Equity, beginning of period at Dec. 31, 2011	7,994		92	3,188	(787)	10,787	(5,286)
Effect of issuing stock for employee benefit plans, Additional Paid In Capital				88
Effect of issuing stock for employee benefit plans, Retained Earnings						(26)
Effect of issuing stock for employee benefit plans, Treasury Stock							110
Effect of issuing stock for employee benefit plans, Total Equity		172
Other comprehensive income (loss) attributable to Parent	116	116			116
Shareholders' net income	751
Net income	751	751				751
Common dividends declared (per share: $0.04)		(11)				(11)
Total Equity, end of period at Jun. 30, 2012		9,022	92	3,276	(671)	11,501	(5,176)
Redeemable Noncontrolling interest, Beginning Balance at Dec. 31, 2012	114
Total Equity, beginning of period at Dec. 31, 2012		9,769	92	3,295	(671)	12,330	(5,277)
Effect of issuing stock for employee benefit plans, Additional Paid In Capital				31
Effect of issuing stock for employee benefit plans, Retained Earnings						(75)
Effect of issuing stock for employee benefit plans, Treasury Stock							146
Effect of issuing stock for employee benefit plans, Total Equity		102
Other comprehensive income (loss) attributable to Parent	(343)	(343)			(343)
Shareholders' net income	562
Net income	565	562				562
Common dividends declared (per share: $0.04)		(11)				(11)
Repurchase of common stock		(304)					(304)
Increase (Decrease) in Temporary Equity [Roll Forward]
Redeemable Noncontrolling interest, Other comprehensive income	(9)
Redeemable Noncontrolling Interest, Net income	3
Redeemable Noncontrolling Interest, Distribution to noncontrolling interest	(7)
Redeemable Noncontrolling interest, Ending Balance at Jun. 30, 2013	101
Total Equity, end of period at Jun. 30, 2013		9,775	92	3,326	(1,014)	12,806	(5,435)
Redeemable Noncontrolling interest, Beginning Balance at Mar. 31, 2013	113
Total Equity, beginning of period at Mar. 31, 2013		9,660	92	3,305	(756)	12,328	(5,309)
Effect of issuing stock for employee benefit plans, Additional Paid In Capital				21
Effect of issuing stock for employee benefit plans, Retained Earnings						(27)
Effect of issuing stock for employee benefit plans, Treasury Stock							81
Effect of issuing stock for employee benefit plans, Total Equity		75
Other comprehensive income (loss) attributable to Parent	(258)	(258)			(258)
Shareholders' net income	505	505				505
Net income	506
Repurchase of common stock		(207)					(207)
Increase (Decrease) in Temporary Equity [Roll Forward]
Redeemable Noncontrolling interest, Other comprehensive income	(6)
Redeemable Noncontrolling Interest, Net income	1
Redeemable Noncontrolling Interest, Distribution to noncontrolling interest	(7)
Redeemable Noncontrolling interest, Ending Balance at Jun. 30, 2013	101
Total Equity, end of period at Jun. 30, 2013		$ 9,775	$ 92	$ 3,326	$ (1,014)	$ 12,806	$ (5,435)