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Investments (Investment Securities Whose Book Value Exceeded Market Value By More Than 5%) (Details) (USD $) In Millions, unless otherwise specified | Mar. 31, 2012
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Schedule of Trading Securities and Other Trading Assets [Line Items] |
Number of Securities | 149
Book Value | $ 2,251
Fair Value | 1,828
5% To Less Than 16% [Member] |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Number of Securities | 23
Book Value | 1,073
Fair Value | 974
Percentage Book Value Exceeded Market Value, Minimum | 5.00%
Percentage Book Value Exceeded Market Value, Maximum | 16.00%
16% To Less Than 26% [Member] |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Number of Securities | 26
Book Value | 796
Fair Value | 656
Percentage Book Value Exceeded Market Value, Minimum | 16.00%
Percentage Book Value Exceeded Market Value, Maximum | 26.00%
26% To 50% [Member] |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Number of Securities | 64
Book Value | 275
Fair Value | 175
Percentage Book Value Exceeded Market Value, Minimum | 26.00%
Percentage Book Value Exceeded Market Value, Maximum | 50.00%
Greater Than 50% [Member] |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Number of Securities | 36
Book Value | 107
Fair Value | $ 23
Percentage Book Value Exceeded Market Value, Minimum | 50.00%

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- Definition Disclosure regarding factors used to determine that the impairment of securities not categorized as trading securities (hence equal to available for sale and held to maturity securities) where cost exceeds fair value. This item contains disclosure of the number of investment positions in the investments determined to be temporarily impaired. + References No definition available. + Details
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- Definition Investments Securities In Unrealized Loss Position For Continuous Twelve Month Period or Longer At Fair Value + References No definition available. + Details
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- Definition Investments Securities In Unrealized Loss Position For Continuous Twelve Month Period or Longer Book Value + References No definition available. + Details
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- Definition Percentage Book Value Exceeded Market Value, Maximum + References No definition available. + Details
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- Details
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