Commitments and Contingencies - Pledged Assets and Funds in Trust (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
AFS securities	$ 4,929	$ 1,572
Debt Securities, Trading, Restricted	51	0
Equity securities	2	36
Investment funds	31	20
Mortgage loans	1,106	914
Short-term investments	68	10
Other investments	38	0
Restricted cash	218	105
Total restricted assets	$ 6,443	$ 2,657

Investment Funds Pledged as Collateral

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- Definition

Other Investments Pledged as Collateral

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- Definition

Short Term Investments Pledged as Collateral

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- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount of restricted investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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Amount of restricted investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

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