Composition of the Company's Loan Portfolio (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans carried at fair value	$ 413	$ 433
Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans carried at fair value	2	2
Residential Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans carried at fair value	411	431
Residential Mortgage Loans \| Residential Nonguaranteed
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans carried at fair value	$ 411	$ 431

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents loan receivable as presented on the statement of financial position which may include mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts, or any other loans which are due the Company as of the balance sheet date.

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