XML 115 R91.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Variable Interest Entities - Additional Information (Detail) - Variable Interest Entity, Not Primary Beneficiary | Dec. 31, 2017 Aircraft
--- | ---
Mainline |
Variable Interest Entity [Line Items] |
Aircraft under operating lease, fixed purchase options | 38
Regional Carrier |
Variable Interest Entity [Line Items] |
Aircraft under operating lease | 158

X
- Definition Number of Aircraft under Operating Lease Agreements with Fixed Price Purchase Options + References No definition available. + Details
Name: | ual_NumberOfAircraftUnderOperatingLeaseAgreementsWithFixedPricePurchaseOptions
Namespace Prefix: | ual_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of aircraft under operating lease agreements with purchase options at prices potentially below fair value. + References No definition available. + Details
Name: | ual_NumberOfAircraftUnderOperatingLeaseAgreementsWithPurchaseOptionsAtPricesPotentiallyBelowFairValue
Namespace Prefix: | ual_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ProductOrServiceAxis=us-gaap_MainlineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ProductOrServiceAxis=us-gaap_RegionalCarrierMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |