CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Millions, except Share data, unless otherwise specified	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	RETAINED EARNINGS
Balance at Dec. 31, 2011		$ 619	$ 18,901	$ (1,012)	$ 2,319
Balance (in shares) at Dec. 31, 2011		619,000,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		4	61
Issuance of common stock through dividend reinvestment, incentive and benefit plans (in shares)		4,000,000
Shares withheld to satisfy tax withholdings		(1)	(19)
Shares withheld to satisfy tax withholdings (in shares)		(1,000,000)
Share-based compensation and other, net			56
Other comprehensive income	14			14
Net income	274				274
Dividends declared					(905)
Balance at Jun. 30, 2012	20,311	622	18,999	(998)	1,688
Balance (in shares) at Jun. 30, 2012		622,000,000
Balance at Dec. 31, 2012	19,289	626	19,079	(1,701)	1,285
Balance (in shares) at Dec. 31, 2012	625,658,000	626,000,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		2	38
Issuance of common stock through dividend reinvestment, incentive and benefit plans (in shares)		2,000,000
Repurchase of common stock	(851)	(24)	(845)
Repurchase of common stock (in shares)	(24,000,000)	(24,000,000)
Shares withheld to satisfy tax withholdings			(16)
Share-based compensation and other, net			35
Other comprehensive income	13			13
Net income	567				567
Dividends declared					(659)
Balance at Jun. 30, 2013	$ 18,400	$ 604	$ 18,291	$ (1,688)	$ 1,193
Balance (in shares) at Jun. 30, 2013	604,209,000	604,000,000