Fair Value of Financial Instruments, Balance Sheet Classification (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Assets	$ 30	$ 10
Liabilities	80	109
Derivatives Designated as Hedges Instruments [Member]
Derivatives, Fair Value [Line Items]
Assets	20	9
Liabilities	75	95
Derivatives Designated as Hedges Instruments [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Assets	15	8
Derivatives Designated as Hedges Instruments [Member] | Non-Current Assets [Member]
Derivatives, Fair Value [Line Items]
Assets	5	1
Derivatives Designated as Hedges Instruments [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liabilities	67	83
Derivatives Designated as Hedges Instruments [Member] | Non-Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liabilities	8	12
Derivatives not Designated as Hedges Instruments [Member]
Derivatives, Fair Value [Line Items]
Assets	10	1
Liabilities	5	14
Derivatives not Designated as Hedges Instruments [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Assets	10	1
Derivatives not Designated as Hedges Instruments [Member] | Non-Current Assets [Member]
Derivatives, Fair Value [Line Items]
Assets	0	0
Derivatives not Designated as Hedges Instruments [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liabilities	5	14
Derivatives not Designated as Hedges Instruments [Member] | Non-Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liabilities	$ 0	$ 0