CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance, at Dec. 31, 2012	$ 4,904	$ 3	$ 7,319	$ (2,108)	$ (310)
Balance, (in shares) at Dec. 31, 2012		286.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	86			86
Other comprehensive income (loss)	(143)				(143)
Conversion of convertible debentures	0
Exercise of stock options and related tax effects	(4)	$ 0	(4)
Exercise of stock options and related tax effects, shares		0.0
Issuance of restricted stock, net of forfeitures and retirements to pay taxes	(7)	$ 0	(7)
Issuance of restricted stock, net of forfeitures and retirements to pay taxes, shares		1.0
Share-based compensation	20		20
Balance, at Dec. 31, 2013	4,856	$ 3	7,328	(2,022)	(453)
Balance, (in shares) at Dec. 31, 2013		287.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	293			293
Other comprehensive income (loss)	204				204
Conversion of convertible debentures	$ 5	$ 0	5
Conversion of convertible debentures, shares	0.5	1.0
Exercise of stock options and related tax effects	$ 6	$ 0	6
Exercise of stock options and related tax effects, shares		0.0
Issuance of restricted stock, net of forfeitures and retirements to pay taxes	(13)	$ 0	(13)
Issuance of restricted stock, net of forfeitures and retirements to pay taxes, shares		1.0
Share-based compensation	24		24
Balance, at Dec. 31, 2014	5,375	$ 3	7,350	(1,729)	(249)
Balance, (in shares) at Dec. 31, 2014		289.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	268			268
Other comprehensive income (loss)	150				150
Conversion of convertible debentures	$ 30	$ 0	30
Conversion of convertible debentures, shares	2.9	3.0
Exercise of stock options and related tax effects	$ 2	$ 0	2
Exercise of stock options and related tax effects, shares		0.0
Repurchases of common stock	(50)	$ 0	(50)
Repurchases of common stock, shares		(2.0)
Issuance of restricted stock, net of forfeitures and retirements to pay taxes	(10)	$ 0	(10)
Issuance of restricted stock, net of forfeitures and retirements to pay taxes, shares		1.0
Share-based compensation	34		34
Balance, at Dec. 31, 2015	$ 5,799	$ 3	$ 7,356	$ (1,461)	$ (99)
Balance, (in shares) at Dec. 31, 2015		291.0