Supplemental Financial Information - Inventory (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Inventory, Net [Abstract]
Work in process and raw materials	$ 273	$ 185
Finished goods	261	190
Service parts	382	405
Total inventories, net	$ 916	$ 780

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.BB)
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- Definition

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

+ References

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-Publisher FASB
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-Section 45
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No definition available.

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- Definition

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date for elements of machinery or equipment held for the purpose of replacing similar parts in the course of repair or maintenance.

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- Definition

The aggregate carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of items which are partially completed at the time of measurement and unprocessed items that will go through the production process and become part of the final product. This element may be used when the reporting entity combines work in process and raw materials into an aggregate amount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(a)(3))
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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.BB)
-URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

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-Subparagraph (SX 210.5-02(6)(a)(4))
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