Revenues from Contracts with Customers - Schedule of Deferred Revenue Reconciliation (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Change In Contract With Customer, Liability [Roll Forward] | |||
| Deferred revenues, beginning of period | $ 78 | $ 36 | $ 40 |
| Cash received but not yet recognized | 110 | 71 | 25 |
| Revenue recognized from prior period deferral | (76) | (29) | (29) |
| Deferred revenues, end of period | $ 112 | $ 78 | $ 36 |
| X | ||||||||||
- Definition Change In Contract With Customer, Liability [Roll Forward] No definition available.
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| X | ||||||||||
- Definition Contract with Customer, Liability, Additions No definition available.
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| X | ||||||||||
- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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