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, 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	40			40
Other comprehensive income (loss)	38				38
Conversion of convertible debentures	0
Exercise of stock options and related tax effects	2	$ 0	2
Exercise of stock options and related tax effects, shares		0.0
Issuance of restricted stock, net of forfeitures and retirements to pay taxes	(9)	$ 0	(9)
Issuance of restricted stock, net of forfeitures and retirements to pay taxes, shares		1.0
Share-based compensation	7		7
Balance, at Mar. 31, 2015	5,453	$ 3	7,350	(1,689)	(211)
Balance, (in shares) at Mar. 31, 2015		290.0
Balance, at Dec. 31, 2015	5,799	$ 3	7,356	(1,461)	(99)
Balance, (in shares) at Dec. 31, 2015		291.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	153			153
Other comprehensive income (loss)	85				85
Conversion of convertible debentures	$ 4	$ 0	4
Conversion of convertible debentures, shares	0.4	1.0
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	(301)	$ 0	(301)
Repurchases of common stock, shares		(13.0)
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	8		8
Balance, at Mar. 31, 2016	$ 5,737	$ 3	$ 7,056	$ (1,308)	$ (14)
Balance, (in shares) at Mar. 31, 2016		280.0