Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Provision/(benefit) for income taxes	$ 45	$ 14	$ 136	$ (230)
Effective tax rates	17.30%	8.30%	19.20%	(102.10%)
Gross cumulative unrecognized tax benefits	99		99		102
Amount that would affect the Company's effective tax rate, if recognized	67		67
Recognized a gross liability for interest related to its UTBs	21		21		21
Interest expense (income) related to UTBs	(1)	(2)	(1)	1
Reasonably possible decrease in UTBs during the next 12 months	$ 10		$ 10
Federal returns examined by the IRS	As of September 30, 2011, the Company’s federal returns through 2006 have been examined by the IRS and all issues have been resolved. The Company’s 2007 through 2009 federal income tax returns are currently under examination by the IRS.

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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The tax year(s) being audited in connection with the income tax examination.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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The estimated upper bound of the reasonably possible change in the total amount of the unrecognized tax benefit (that will significantly increase or decrease within twelve months of the balance sheet date) for a tax position taken.

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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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-Glossary Unrecognized Tax Benefit

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This element represents the amount of interest expense accrued as of the date of the statement of financial position for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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