Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2016
Revenue from Contract with Customer [Abstract]
Contract assets included in prepaid and other current assets	$ 19	$ 26
Contract liabilities included in accrued liabilities	(2)	(1)
Contract liabilities included in other non-current liabilities	(6)	(7)
Net contract asset	$ 11	$ 18

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

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-Publisher FASB
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- Definition

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

+ References

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-Publisher FASB
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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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- References

No definition available.

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