Supplemental Disclosures of Cash Flow Information and Non-Cash Investing and Financing Activities (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash paid (refunded) during the period for:
Interest (net of amounts capitalized)	$ 748us-gaap_InterestPaidNet	$ 752us-gaap_InterestPaidNet	$ 766us-gaap_InterestPaidNet
Income taxes	(16)us-gaap_IncomeTaxesPaidNet	(20)us-gaap_IncomeTaxesPaidNet	2us-gaap_IncomeTaxesPaidNet
Non-cash transactions:
Net property and equipment acquired through issuance of debt	1,114	229	544
8% Contingent Senior Notes and 6% Senior Notes due 2031, net of discount			357us-gaap_NotesIssued1
Special facility payment financing			101
Airport construction financing	14ual_NonCashAirportConstructionFinancing	40ual_NonCashAirportConstructionFinancing	50ual_NonCashAirportConstructionFinancing
Exchanges of certain 4.5% Note and 6% Convertible Senior Notes for common stock		240
UAL 4.5% and 6% Senior Convertible Notes
Non-cash transactions:
Exchanges of certain 4.5% Note and 6% Convertible Senior Notes for common stock	260
United Airlines, Inc.
Cash paid (refunded) during the period for:
Interest (net of amounts capitalized)	748	752	766
Income taxes	(16)	(15)	4
Non-cash transactions:
Net property and equipment acquired through issuance of debt	1,114	229	544
8% Contingent Senior Notes and 6% Senior Notes due 2031, net of discount			357
Special facility payment financing			101
Airport construction financing	14	40	50
Transfer of UAL subsidiaries to United	186
United Airlines, Inc. \| UAL 4.5% and 6% Senior Convertible Notes
Non-cash transactions:
Exchanges of certain 4.5% Note and 6% Convertible Senior Notes for common stock	$ 156

Non Cash Airport Construction Financing

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- Definition

Noncash special facility payment financing. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period.

+ References

No definition available.

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- Definition

The amount of the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

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The amount of cash paid for interest during the period net of cash paid for interest that is capitalized.

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- Definition

The amount of fixed assets that an Entity acquires in a noncash (or part noncash) acquisition. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

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- Definition

The fair value of notes issued in noncash investing and financing activities.

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- Definition

Value of investments transferred from the entity's investments in noncash transactions.

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