CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Millions, unless otherwise specified	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE (LOSS)	RETAINED EARNINGS
Balance at Dec. 31, 2010		$ 305	$ 6,181	$ (141)	$ 3,302
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		1	18
Shares withheld to satisfy tax withholdings			(15)
Share-based compensation and other, net			16
Other comprehensive income	2			2
Net income	211				211
Dividends declared					(222)
Balance at Mar. 31, 2011	9,658	306	6,200	(139)	3,291
Balance at Dec. 31, 2011	20,827	619	18,901	(1,012)	2,319
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		2	33
Shares withheld to satisfy tax withholdings			(11)
Share-based compensation and other, net			27
Other comprehensive income	12			12
Net income	200				200
Dividends declared					(452)
Balance at Mar. 31, 2012	$ 20,638	$ 621	$ 18,950	$ (1,000)	$ 2,067