Loans and asset quality- Nonperforming Assets (Parenthetical) (Detail) (Investment Management Funds, Nonperforming Financing Receivable, USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investment Management Funds \| Nonperforming Financing Receivable
Financing Receivable, Impaired [Line Items]
Loans fair value	$ 161	$ 174

- 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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