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, 2012		$ 626	$ 19,079	$ (1,701)	$ 1,285
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		4	69
Repurchase of common stock		(46)	(1,551)
Shares withheld to satisfy tax withholdings			(18)
Share-based compensation and other, net			85
Other comprehensive income (loss)				899
Dividends declared			(321)		(980)
Net income (loss)	$ (239)				(239)
Balance at end of period at Dec. 31, 2013	17,191	584	17,343	(802)	66
Increase (Decrease) in Stockholders' Equity
Issuance of common stock through dividend reinvestment, incentive and benefit plans		4	46
Repurchase of common stock		(19)	(591)
Shares withheld to satisfy tax withholdings			(16)
Share-based compensation and other, net			82
Other comprehensive income (loss)	(1,215)			(1,215)
Dividends declared			(540)		(691)
Net income (loss)	772				772
Balance at end 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		(27)	(767)
Shares withheld to satisfy tax withholdings			(19)
Share-based compensation and other, net			77
Other comprehensive income (loss)	83			83
Dividends declared			(446)		(753)
Net income (loss)	878				878
Balance at end of period at Dec. 31, 2015	$ 14,060	$ 544	$ 15,178	$ (1,934)	$ 272