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Investments (Distribution Of Held To Maturity Investments By Contractual Maturity) (Detail) (USD $) In Millions, unless otherwise specified | Jun. 30, 2012 | Dec. 31, 2011
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Held-To-Maturity [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Due in one year or less, Fair Value |  |  |
Due after one year through five years, Fair Value | 1 | [1] |
Due after five years through ten years, Fair Value |  |  |
Due after ten years through fifteen years, Fair Value |  |  |
Due after fifteen years, Fair Value |  |  |
Total held-to-maturity investments, Fair Value | 1 |  |
Due in one year or less, Amortized Cost |  |  |
Due after one year through five years, Amortized Cost | 1 | [1] |
Due after five years through ten years, Amortized Cost |  |  |
Due after ten years through fifteen years, Amortized Cost |  |  |
Due after fifteen years, Amortized Cost |  |  |
Total held-to-maturity investments, Amortized Cost | 1 |  |
Variable Interest Entity [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Total held-to-maturity investments, Fair Value | 2,896 |  | 3,489
Total held-to-maturity investments, Amortized Cost | 3,051 |  | 3,843
Variable Interest Entity [Member] | Held-To-Maturity [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Due in one year or less, Fair Value |  |  |
Due after five years through ten years, Fair Value |  |  |
Due after ten years through fifteen years, Fair Value |  |  |
Due after fifteen years, Fair Value |  |  |
Total held-to-maturity investments, Fair Value | 2,896 |  |
Due in one year or less, Amortized Cost |  |  |
Due after five years through ten years, Amortized Cost |  |  |
Due after ten years through fifteen years, Amortized Cost |  |  |
Due after fifteen years, Amortized Cost |  |  |
Total held-to-maturity investments, Amortized Cost | 3,051 |  |
Variable Interest Entity [Member] | Asset-Backed Securities [Member] | Held-To-Maturity [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Total held-to-maturity investments, Fair Value | 2,896 |  |
Total held-to-maturity investments, Amortized Cost | $ 3,051 |  |
[1] | Relates to tax credit investments reported in "Other investments" on the Company's consolidated balance sheets.

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- Definition For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Section A -Paragraph 5 -Chapter 3 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. 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