Defined Benefit Plan, Employer Contribution, Percentage

No definition available.

Name:	ual_DefinedBenefitPlanEmployerContributionPercentage
Namespace Prefix:	ual_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan Profit Sharing And Payroll Tax Expense

+ References

No definition available.

+ Details

Name:	ual_DefinedBenefitPlanProfitSharingAndPayrollTaxExpense
Namespace Prefix:	ual_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Multiemployer Pension Employer Percentage

+ References

No definition available.

+ Details

Name:	ual_MultiemployerPensionEmployerPercentage
Namespace Prefix:	ual_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Profit Sharing Plan, Percentage of Pre-Tax Earnings Paid

+ References

No definition available.

+ Details

Name:	ual_ProfitSharingPlanPercentageOfPreTaxEarningsPaid
Namespace Prefix:	ual_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Definition

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contributions made to the multiemployer plan by all employers who participate in the plan. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 7

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450678-114947

+ Details

Name:	us-gaap_MultiemployerPlansPlanContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=ual_UnitedAirLinesIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=us-gaap_MultiemployerPlansPensionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Pension and Other Postretirement Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Effect on post retirement benefit obligation, 1% Decrease	$ 247
Effect on total service and interest cost, 1% Decrease	10
Profit sharing and payroll tax expense	235	190	119
Multiemployer Plans, Pension \| IAM National Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Multi-employer plan contributions		368
Minimum
Defined Benefit Plan Disclosure [Line Items]
Percentage of pre-tax earnings paid for profit sharing plan	5.00%
Minimum \| Multiemployer Plans, Pension \| IAM National Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Percent of company's contribution to plan		5.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of pre-tax earnings paid for profit sharing plan	20.00%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Effect on post retirement benefit obligation, 1% Decrease	(220)
Effect on total service and interest cost, 1% Decrease	(11)
Employer contributions	144	128
Other Postretirement Benefits \| Deposit Administration Fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets	100.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	307	277
United Airlines, Inc.
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	503	433	330
United Airlines, Inc. \| Multiemployer Plans, Pension \| IAM National Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Multi-employer plan contributions	39	38	36
United Airlines, Inc. \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Employer contribution, percentage	1.00%
United Airlines, Inc. \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Employer contribution, percentage	16.00%
United Airlines, Inc. \| Other Postretirement Benefits \| Scenario Forecast
Defined Benefit Plan Disclosure [Line Items]
Employer contributions				120
United Airlines, Inc. \| Pension Benefits \| Minimum \| Scenario Forecast
Defined Benefit Plan Disclosure [Line Items]
Employer contributions				$ 400