Earnings Per Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Abstract]
Antidilutive securities excluded (in shares)			1,900,000	2,400,000
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Income from continuing operations	$ 73	$ 65	$ 34	$ 73
Numerator:
Income from continuing operations available to common stockholders	74	66	34	73
Loss from discontinued operation	0	0	0	(1)
Net income available to common stockholders	74	66	34	72
Denominator:
Denominator for basic earnings per share—weighted-average common shares (in shares)	92,539,000	62,640,000	79,681,000	61,996,000
Denominator for diluted earnings per share—adjusted weighted-average common shares (in shares)	105,273,000	73,334,000	91,500,000	73,434,000
Basic earnings per share:
Income from continuing operations (in dollars per share)	$ 0.78	$ 1.04	$ 0.42	$ 1.18
Loss from discontinued operation (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ (0.01)
Net income (in dollars per share)	$ 0.78	$ 1.04	$ 0.42	$ 1.17
Diluted earnings per share:
Income from continuing operations (in dollars per share)	$ 0.70	$ 0.91	$ 0.37	$ 1.00
Loss from discontinued operation (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ (0.01)
Net income (in dollars per share)	$ 0.70	$ 0.91	$ 0.37	$ 0.99
Employee stock options and warrants [Member]
Denominator:
Incremental common shares attributable to share-based payment arrangements (in shares)	707,000	633,000	759,000	1,215,000
Convertible debt interest - 1 7/8 percent notes [Member]
Numerator:
Convertible debt interest	0	0	0	0
Denominator:
Convertible subordinated notes (in shares)	208,000	1,015,000	0	1,015,000
Subordinated convertible debt interest [Member]
Numerator:
Convertible debt interest	$ 1	$ 1	$ 0	$ 0
Convertible subordinated notes - 4 percent [Member]
Denominator:
Convertible subordinated notes (in shares)	10,031,000	6,379,000	10,543,000	8,578,000
Subordinated convertibe debentures [Member]
Denominator:
Convertible subordinated notes (in shares)	1,341,000	2,122,000	0	0
Restricted stock units [Member]
Denominator:
Incremental common shares attributable to share-based payment arrangements (in shares)	447,000	545,000	517,000	630,000