CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE LOSS	RETAINED EARNINGS
Balance at beginning of period at Dec. 31, 2013		$ 584	$ 17,343	$ (802)	$ 66
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		4	43
Repurchase of common stock		(17)	(497)
Shares withheld to satisfy tax withholdings			(15)
Other comprehensive income	$ 13			13
Net income	584				584
Dividends declared			(405)		(519)
Share-based compensation and other, net			63
Balance at end of period at Sep. 30, 2014	16,445	571	16,532	(789)	131
Balance at beginning of period at Dec. 31, 2014	15,023	569	16,324	(2,017)	147
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		2	9
Repurchase of common stock		(17)	(518)
Shares withheld to satisfy tax withholdings			(18)
Other comprehensive income	76			76
Net income	540				540
Dividends declared			(395)		(510)
Share-based compensation and other, net			58
Balance at end of period at Sep. 30, 2015	$ 14,250	$ 554	$ 15,460	$ (1,941)	$ 177