Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Fair value, before effects of master netting arrangements, of a financial liability or 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 liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Basis Of Presentation Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Foreign Exchange Contract
Derivative [Line Items]
Notional amount of derivative instrument	$ 28		$ 28		$ 27
Foreign Exchange Contract \| Not Designated as Hedging Instrument \| Operating Expense [Member]
Derivative [Line Items]
Location of (Gain) or Loss Recognized for Derivative Instruments	0	$ 1	0	$ 1
Foreign Exchange Contract \| Maximum
Derivative [Line Items]
Fair value of derivative instrument	1		1		1
Interest Rate Swap
Derivative [Line Items]
Notional amount of derivative instrument	1,600		1,600
Interest Rate Swap \| Not Designated as Hedging Instrument \| Interest expense
Derivative [Line Items]
Location of (Gain) or Loss Recognized for Derivative Instruments	24	$ 0	38	$ (12)
Interest Rate Swap \| Not Designated as Hedging Instrument \| Other non-current assets
Derivative [Line Items]
Interest rate swap contract - other non-current assets	0		0		6
Interest Rate Swap \| Not Designated as Hedging Instrument \| Other non-current liabilities
Derivative [Line Items]
Interest rate swap contract - other current and non-current liabilities	48		48		$ 16
Interest Rate Swap \| August 2015
Derivative [Line Items]
Notional amount of derivative instrument	600		600
Interest Rate Swap \| November 2017
Derivative [Line Items]
Notional amount of derivative instrument	450		450
Interest Rate Swap \| August 2020
Derivative [Line Items]
Notional amount of derivative instrument	400		400
Interest Rate Swap \| November 2022
Derivative [Line Items]
Notional amount of derivative instrument	$ 150		$ 150