Debt Instrument Date Principal Due

No definition available.

Name:	ual_DebtInstrumentDatePrincipalDue
Namespace Prefix:	ual_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of borrowing capacity currently available under the debt instrument (initial borrowing capacity less the amount of proceeds received).

+ References

No definition available.

+ Details

Name:	ual_RemainingProceedsFromBorrowings
Namespace Prefix:	ual_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
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 of Pass Through Trusts (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Total debt recorded	$ 248us-gaap_DebtInstrumentCarryingAmount
Proceeds received from issuance of debt	1,432	1,423	1,121
United Airlines, Inc.
Debt Instrument [Line Items]
Total debt recorded	11,533	11,604
Proceeds received from issuance of debt	1,432	1,423	1,121
United Airlines, Inc. \| Class A Pass Through Certificates \| August 2014
Debt Instrument [Line Items]
Principal	823
Final expected distribution date	2026-09
Stated interest rate	3.75%
Total debt recorded	112
Proceeds received from issuance of debt	112
Remaining proceeds from issuance of debt to be received in future periods	711
United Airlines, Inc. \| Class A Pass Through Certificates \| April 2014
Debt Instrument [Line Items]
Principal	736
Final expected distribution date	2026-04
Stated interest rate	4.00%
Total debt recorded	736
Proceeds received from issuance of debt	736
United Airlines, Inc. \| Class A Pass Through Certificates \| August 2013
Debt Instrument [Line Items]
Principal	720
Final expected distribution date	2025-08
Stated interest rate	4.30%
Total debt recorded	720
Proceeds received from issuance of debt	567
United Airlines, Inc. \| Class B Pass Through Certificates \| August 2014
Debt Instrument [Line Items]
Principal	238
Final expected distribution date	2022-09
Stated interest rate	4.625%
Total debt recorded	32
Proceeds received from issuance of debt	32
Remaining proceeds from issuance of debt to be received in future periods	206
United Airlines, Inc. \| Class B Pass Through Certificates \| April 2014
Debt Instrument [Line Items]
Principal	213
Final expected distribution date	2022-04
Stated interest rate	4.75%
Total debt recorded	213
Proceeds received from issuance of debt	213
United Airlines, Inc. \| Class B Pass Through Certificates \| August 2013
Debt Instrument [Line Items]
Principal	209
Final expected distribution date	2021-08
Stated interest rate	5.375%
Total debt recorded	209
Proceeds received from issuance of debt	165
United Airlines, Inc. \| EETC
Debt Instrument [Line Items]
Principal	2,939
Total debt recorded	2,022
Proceeds received from issuance of debt	1,825
Remaining proceeds from issuance of debt to be received in future periods	$ 917