Earnings (Loss) Per Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Antidilutive securities excluded (in shares)	0	13,500,000	600,000	14,000,000
Numerator:
Net income (loss) available to common stockholders	$ 83	$ (52)	$ 104	$ (39)
Denominator:
Denominator for basic earnings per share—weighted-average common shares (in shares)	93,895,000	83,231,000	93,604,000	73,181,000
Denominator for diluted earnings per share—adjusted weighted-average common shares (in shares)	106,715,000	83,231,000	106,557,000	73,181,000
Basic earnings (loss) per share (in dollars per share)	$ 0.89	$ (0.63)	$ 1.12	$ (0.53)
Diluted earnings (loss) per share (in dollars per share)	$ 0.78	$ (0.63)	$ 0.98	$ (0.53)
Employee stock options and warrants [Member]
Denominator:
Incremental common shares attributable to share-based payment arrangements (in shares)	498,000	0	557,000	0
Convertible subordinated notes - 4 percent [Member]
Denominator:
Convertible subordinated notes (in shares)	11,946,000	0	11,908,000	0
Restricted stock units [Member]
Denominator:
Incremental common shares attributable to share-based payment arrangements (in shares)	376,000	0	488,000	0
Convertible subordinated notes - 4 percent [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Stated interest rate	4.00%		4.00%