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Tax - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reconciliation Of Statutory Federal Tax Rate [Line Items]
Effective tax rate	31.00%	32.10%	31.00%	31.50%
U.S. federal statutory rate			35.00%
Unrecognized tax benefit	$ 128		$ 128
Realized [Member]
Reconciliation Of Statutory Federal Tax Rate [Line Items]
Unrecognized tax benefit	$ 55		$ 55

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

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-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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-Name Accounting Standards Codification

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854



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