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Investments (Distribution Of Held To Maturity Investments By Contractual Maturity) (Details) (USD $) In Millions, unless otherwise specified | Mar. 31, 2012 | Dec. 31, 2011
--- | --- | ---
Variable Interest Entity [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Total held-to-maturity investments, Amortized Cost | $ 3,093 |  | $ 3,843
Total held-to-maturity investments, Fair Value | 2,871 |  | 3,489
Held-To-Maturity [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Due in one year or less, Amortized Cost |  |  |
Due in one year or less, Fair Value |  |  |
Due after one year through five years, Amortized Cost | 1 | [1] |
Due after one year through five years, Fair Value | 1 | [1] |
Due after five years through ten years, Amortized Cost |  |  |
Due after five years through ten years, Fair Value |  |  |
Due after ten years through fifteen years, Amortized Cost |  |  |
Due after ten years through fifteen years, Fair Value |  |  |
Due after fifteen years, Amortized Cost |  |  |
Due after fifteen years, Fair Value |  |  |
Total held-to-maturity investments, Amortized Cost | 1 |  |
Total held-to-maturity investments, Fair Value | 1 |  |
Held-To-Maturity [Member] | Mortgage-Backed Securities [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Total held-to-maturity investments, Amortized Cost |  |  |
Total held-to-maturity investments, Fair Value |  |  |
Held-To-Maturity [Member] | Variable Interest Entity [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Due in one year or less, Amortized Cost |  |  |
Due in one year or less, Fair Value |  |  |
Due after five years through ten years, Amortized Cost |  |  |
Due after five years through ten years, Fair Value |  |  |
Due after ten years through fifteen years, Amortized Cost |  |  |
Due after ten years through fifteen years, Fair Value |  |  |
Due after fifteen years, Amortized Cost |  |  |
Due after fifteen years, Fair Value |  |  |
Total held-to-maturity investments, Amortized Cost | 3,093 |  |
Total held-to-maturity investments, Fair Value | 2,871 |  |
Held-To-Maturity [Member] | Variable Interest Entity [Member] | Mortgage-Backed Securities [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Total held-to-maturity investments, Amortized Cost |  |  |
Total held-to-maturity investments, Fair Value |  |  |
Held-To-Maturity [Member] | Variable Interest Entity [Member] | Asset-Backed Securities [Member] |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Total held-to-maturity investments, Amortized Cost | 3,093 |  |
Total held-to-maturity investments, Fair Value | $ 2,871 |  |
[1] | Relates to tax credit investments reported in "Other investments" on the Company's consolidated balance sheets.

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