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LEASES LEASES - OPERATING LEASE ASSETS (Details) - USD ($) $ in Millions | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Lessee, Lease, Description [Line Items] |  |
Operating Lease, Right-of-Use Asset | $ 1,647 | $ 0
Aircraft [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating Lease, Right-of-Use Asset | 974 |
CPA Aircraft [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating Lease, Right-of-Use Asset | 609 |
Airport Facilities [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating Lease, Right-of-Use Asset | 18 |
Corporate real estate [Member] |  |
Lessee, Lease, Description [Line Items] |  |
Operating Lease, Right-of-Use Asset | $ 46 |

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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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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |