Derivative financial instruments - Offsetting assets (Details 3) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivatives
Gross amount of recognized assets	$ 336	$ 322
Derivative liabilities eligible for set-off in case of default	(215)	(216)
Net asset exposure	121	106
Reverse repurchase agreements
Gross amount of recognized assets	224	219
Non-cash collateral received	(224)	(219)
Total
Gross amount of recognized assets	560	541
Derivative liabilities eligible for set-off in case of default	(215)	(216)
Non-cash collateral received	(224)	(219)
Net asset exposure	$ 121	$ 106

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226003-175313

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- References

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Amount, after effects of master netting arrangements, of derivative assets, securities purchased under agreements to resell and securities borrowed offset against an obligation to return collateral under a master netting arrangement. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of obligation to return securities collateral under master netting arrangements that have not been offset against derivative assets, securities purchased under agreements to resell and securities borrowed.

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Amount, before effects of master netting arrangements, of derivative assets, securities purchased under agreements to resell and securities borrowed. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

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Amount of liability associated with derivative assets, securities purchased under agreements to resell and securities borrowed.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

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Fair value, after effects of master netting arrangements, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against an obligation to return collateral. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount of obligation to return securities collateral under master netting arrangements that have not been offset against securities purchased under agreement to resell.

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Amount, before effects of master netting arrangements, of funds outstanding loaned in the form of a security resale agreement between the entity and another party for the purchase and resale of identical or substantially the same securities at a date certain for a specified price. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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