Components of Accumulated Other Comprehensive Income (Loss), Net of Tax (Parenthetical) (Detail) (United Airlines, Inc., USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
United Airlines, Inc.
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax (expense) benefit		$ 6	$ 6
Additional (losses) gains related to investments and other	$ 1		$ 1

Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 31

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 20

-Section 45

-Paragraph 11

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=18498875&loc=d3e39076-109324

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e640-108580

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