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Income Taxes - Schedule of Changes in Valuation Allowance (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Valuation Allowance [Line Items] |  |  |
Balance at beginning of year | $ 2,486 | $ 2,584 | $ 1,940
Increase to allowance | 37 | 136 | 831
Release of allowance | (222) | (154) | (246)
Acquisitions and divestitures (F) | (2) | 0 | (1)
Tax apportionment, tax rate and tax law changes | (13) | (14) | (24)
Foreign currency translation | (30) | (66) | 84
Balance at end of year | 2,256 | 2,486 | $ 2,584
Other Net State Deferred Tax Asset |  |  |
Valuation Allowance [Line Items] |  |  |
Balance at beginning of year | $ 672 |  |
Balance at end of year |  | $ 672 |

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- Definition Deferred tax assets valuation acquisitions divestitures. + References No definition available. + Details
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- Definition Deferred tax assets valuation foreign currency translation. + References No definition available. + Details
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- Definition Deferred tax assets valuation release of allowance. + References No definition available. + Details
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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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319 + Details
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- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=116821951&loc=d3e32123-109318 + Details
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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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