Financial Instruments - Schedule of fair value associated with derivative financial instruments (Details) - Level 2 - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Derivative Assets
Gross Fair Value	$ 874	$ 1,093
Impact of Netting	(21)	(44)
Derivative Liabilities
Gross Fair Value	(22)	(45)
Impact of Netting	21	44
Current assets
Derivative Assets
Derivatives instruments	672	752
Non-current assets
Derivative Assets
Derivatives instruments	181	297
Current liabilities
Derivative Liabilities
Derivatives instruments	(1)	(1)
Non-current liabilities
Derivative Liabilities
Derivatives instruments	$ 0	$ 0

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.

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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 offset of derivative liability, 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, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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