Revenue - Additional Information (Detail) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($)
Disaggregation Of Revenue [Line Items]
Deferred revenue recognized	$ 12
Maximum [Member]
Disaggregation Of Revenue [Line Items]
Expected recognition period of revenue	1 year
Amortization period of revenue recognized	1 year
Accounting Standards Update 2014-09 [Member] \| Receivables and Deferred Revenue [Member]
Disaggregation Of Revenue [Line Items]
Additional receivables and deferred revenue related to recognition of receivables with unconditional right to payment	$ 2

Amortization period of revenue recognized.

No definition available.

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- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

+ References

No definition available.

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- Definition

Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

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