Leases And Capacity Purchase Agreements (Future Lease Payment Under Terms Of Capacity Purchase Agreement) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Leases And Capacity Purchase Agreements [Abstract]
2012	$ 1,653
2013	1,568
2014	1,403
2015	1,261
2016	1,022
After 2016	2,855
Future payments under CAP	$ 9,762

Future Payments Under The Terms Of Capacity Purchase Agreements Due Five And Thereafter

No definition available.

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

Future Payments Under The Terms Of Capacity Purchase Agreements Due Five Year

No definition available.

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

Future Payments Under The Terms Of Capacity Purchase Agreements Due Four Year

No definition available.

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

Future Payments Under The Terms Of Capacity Purchase Agreements Due One Year

No definition available.

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

Future Payments Under The Terms Of Capacity Purchase Agreements Due Three Year

No definition available.

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

Future Payments Under The Terms Of Capacity Purchase Agreements Due Two Year

No definition available.

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

Future Payments Under Terms Of Capacity Purchase Agreements In Total

No definition available.

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

Name:	ual_LeasesAndCapacityPurchaseAgreementsAbstract
Namespace Prefix:	ual_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration