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Schedule II: Valuation and Qualifying Accounts Parenthetical XBRL Tags (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
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Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Valuation Allowance | $ 162 | $ 126 | $ 6
Valuation Allowance of Deferred Tax Assets [Member] | Acquisitions [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Valuation Allowance | $ 48 | $ 4 | $ 4

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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32537-109319 + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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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. + Details
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- Details
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Namespace Prefix: |
Data Type: | na
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- Details
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Namespace Prefix: |
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Balance Type: |
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