Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 118		$ 280		$ 44		$ 336
Interest on Convertible Debt, Net of Tax	1		1		1		4
Net Income (Loss) Available to Common Stockholders, Diluted	$ 119		$ 281		$ 45		$ 340
Weighted Average Number of Shares Outstanding, Basic	108.3		106.8		108.1		106.5
Weighted Average Number Diluted Shares Outstanding Adjustment	3.3	[1],[2]	2.3	[1],[2]	3.3	[1],[2]	2.2	[1],[2]
Incremental Common Shares Attributable to Conversion of Debt Securities	4.6	[2]	8.9	[2]	5.5	[2]	14.0	[2]
Weighted Average Number of Shares Outstanding, Diluted	116.2		118.0		116.9		122.7
Basic (US$ per share)	$ 1.09		$ 2.62		$ 0.41		$ 3.16
Diluted (US$ per share)	$ 1.02		$ 2.38		$ 0.39		$ 2.77
Warrants [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive shares							8.9
Options [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive shares							0.2

[1] For the three and nine months ended September 30, 2012, 0.2 million outstanding options and 8.9 million warrants have an anti-dilutive effect and therefore are excluded from the computation of diluted weighted average shares outstanding.

[2]