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Investments (Distribution Of Held-To-Maturity Investments By Contractual Maturity) (Detail) (USD $) In Millions, unless otherwise specified | Sep. 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 | 2,867 |  | 3,489
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 | 2,867 |  |
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 | 3,015 |  |
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 | 2,867 |  |
Total held-to-maturity investments, Amortized Cost | $ 3,015 |  |
[1] | Relates to tax credit investments reported in "Other investments" on the Company's consolidated balance sheets.

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- Definition Amount of held-to-maturity debt securities at fair value maturing in the eleventh fiscal year through the fifteenth fiscal year following the latest fiscal year. + References No definition available. + Details
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- Definition Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, maturing in the tenth through fifteenth fiscal year following the latest fiscal year. + References No definition available. + Details
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- Definition Amount of held-to-maturity debt securities at fair value maturing after the fifteenth fiscal year following the latest fiscal year. + References No definition available. + Details
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- Definition Amount of held-to-maturity debt securities at fair value maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 20 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27232-111563 + Details
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- Definition Amount of held-to-maturity debt securities at fair value maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 20 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27232-111563 + Details
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