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Commitments, Contingencies and Guarantees (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Commitments, Contingencies And Guarantees [Abstract]
Aggregate loss on securities	$ 42
Maximum aggregate loss, if securities' price falls to zero and no debts collected	$ 51

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- Definition

Maximum Aggregate Loss, If Securities' Price Falls To Zero And No Debts Collected

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No definition available.

+ Details

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- References

No definition available.

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- Definition

Amount of unrealized and realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

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No definition available.

+ Details

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