Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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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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- Definition

Amount of an unrecognized tax benefit that is directly related to a position taken in a tax year that results in a net operating loss carryforward. This amount is presented as a reduction of the related deferred tax asset in the balance sheet if that deferred tax asset is not used. This amount is presented separately from the deferred tax asset for a net operating loss carryforward if this unrelated tax benefit is associated with a different tax position.

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Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012 United States [Member]	Jun. 30, 2013 Federal [Member]	Jun. 30, 2013 State [Member]
Income Tax [Line Items]
Income tax expense (benefit)	$ 47	$ 21	$ 59	$ 39
Net tax benefits related to US taxable income	13		13
Deferred tax assets related to NOL's	90		90
Impact on earnings related to reversal of valuation allowance					81
Federal net operating loss					$ 190
NOL's expiration period						tax years ending in 2022 through 2030	various tax years through 2032