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Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Receivables, allowance for doubtful accounts | $ 7 | $ 10
Aircraft fuel, spare parts and supplies, obsolescence allowance | 354 | 295
Intangibles, accumulated amortization | $ 1,313 | $ 1,234
Common stock, par value | $ 0.01 | $ 0.01
Common shares, authorized | 1,000,000,000 | 1,000,000,000
Common shares, outstanding | 286,973,195 | 314,612,744
United Airlines, Inc. |  |
Receivables, allowance for doubtful accounts | $ 7 | $ 10
Aircraft fuel, spare parts and supplies, obsolescence allowance | 354 | 295
Intangibles, accumulated amortization | $ 1,313 | $ 1,234
Common stock, par value | $ 0.01 | $ 0.01
Common shares, authorized | 1,000 | 1,000
Common shares, issued | 1,000 | 1,000
Common shares, outstanding | 1,000 | 1,000

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- Definition The amount of the valuation account as of the balance sheet date which reduces the carrying amount of airline related inventory (including expendable merchandise, goods, commodities, or supplies to be used primarily in air transport of passengers or freight) to net realizable value; takes into consideration such factors as market value, excessive quantities based on expected sales, technological obsolescence, and shrinkage. + References No definition available. + Details
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- Definition A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524 + Details
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- Definition Face amount or stated value per share of common stock. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 + Details
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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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