The fair value of collateral received by the entity associated with securities borrowed that must be returned if the counterparty fulfills its obligations. It appears on the balance sheet as a liability and has a corresponding asset that appears on the balance sheet called Securities Received as Collateral.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for repurchase agreements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

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Amount of secured borrowings in excess of (less than) the liability for repurchase agreements and securities lending transactions, before offset, included in offsetting disclosures.

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The carrying amount (fair value) as of the balance sheet date of securities held that had been pledged by counterparties under financing and lending arrangements, pursuant to which the entity has the right by agreement or custom to sell or re-pledge such securities.

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Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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.

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No definition available.

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Commitments, contingencies, and guarantees Commitments, Contingencies, And Guarantees (Collateral pledged under repurchase agreements) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	$ 1,406	$ 1,404
Assets pledged under repurchase agreements	1,464	1,459
Securities lending collateral	1,140	1,046
Securities lending payable	1,141	$ 1,047
U.S. Treasury And Agency [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	237
Collateralized Mortgage Backed Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	1,227
Repurchase Agreements [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	58
Overnight and Continuous [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Secured Borrowings, Gross, Difference, Amount	1
Overnight and Continuous [Member] \| Cash and Cash Equivalents [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	449
Overnight and Continuous [Member] \| Corporate [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	4
Overnight and Continuous [Member] \| U.S. Treasury And Agency [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	53
Overnight and Continuous [Member] \| Collateralized Mortgage Backed Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending collateral	38
Maturity Less than 30 Days [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	413
Maturity Less than 30 Days [Member] \| U.S. Treasury And Agency [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	5
Maturity Less than 30 Days [Member] \| Collateralized Mortgage Backed Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	408
Maturity 30 to 90 Days [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	484
Maturity 30 to 90 Days [Member] \| U.S. Treasury And Agency [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	0
Maturity 30 to 90 Days [Member] \| Collateralized Mortgage Backed Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	484
Maturity Greater than 90 Days [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	567
Maturity Greater than 90 Days [Member] \| U.S. Treasury And Agency [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	232
Maturity Greater than 90 Days [Member] \| Collateralized Mortgage Backed Securities [Member]
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Assets pledged under repurchase agreements	$ 335