Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013 Counterparty	Dec. 31, 2012
Derivative [Line Items]
Number of counterparties	17
Net gain included in accumulated other comprehensive loss, after tax	$ (123)	$ (131)
Realization of gains and losses on hedges in future earnings	2014
Cash Flow Hedges [Member]
Derivative [Line Items]
Net gain included in accumulated other comprehensive loss, before tax applied to next twelve months	2
Net gain included in accumulated other comprehensive loss, after tax	$ 1

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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