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 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	28	28		36		(57)	49
Other comprehensive income (loss)	88	87			87			1
Net income	526	528				528		(2)
Common dividends declared (per share: $0.04)	(11)	(11)				(11)
Repurchase of common stock	(643)	(643)					(643)
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(3)
Net income	3
Ending Balance at Mar. 31, 2014	96
Total Equity, end of period at Mar. 31, 2014	10,569	10,556	92	3,392	(433)	14,136	(6,631)	13
Beginning Balance at Dec. 31, 2014	90
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	62	62		55		(177)	184
Other comprehensive income (loss)	2	2			2
Net income	531	533				533		(2)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(418)	(418)					(418)
Capital contribution by noncontrolling interest	2	(1)		(1)				3
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(9)
Capital contribution by noncontrolling interest	2
Ending Balance at Mar. 31, 2015	83
Total Equity, end of period at Mar. 31, 2015	$ 10,958	$ 10,942	$ 74	$ 2,823	$ (934)	$ 10,635	$ (1,656)	$ 16