Details of Pass Through Trusts (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Debt Instrument [Line Items]
Proceeds received from issuance of debt	$ 755	$ 42
United Airlines, Inc.
Debt Instrument [Line Items]
Proceeds received from issuance of debt	755	$ 42
United Airlines, Inc. \| Class AA Pass Through Certificates \| September 2016
Debt Instrument [Line Items]
Principal	$ 637
Final expected distribution date	2028-10
Stated interest rate	2.875%
Total debt recorded	$ 253
Proceeds received from issuance of debt	173
Remaining proceeds from issuance of debt to be received in future periods	384
United Airlines, Inc. \| Class AA Pass Through Certificates \| June 2016
Debt Instrument [Line Items]
Principal	$ 729
Final expected distribution date	2028-07
Stated interest rate	3.10%
Total debt recorded	$ 729
Proceeds received from issuance of debt	319
United Airlines, Inc. \| Class A Pass Through Certificates \| September 2016
Debt Instrument [Line Items]
Principal	$ 283
Final expected distribution date	2028-10
Stated interest rate	3.10%
Total debt recorded	$ 112
Proceeds received from issuance of debt	76
Remaining proceeds from issuance of debt to be received in future periods	171
United Airlines, Inc. \| Class A Pass Through Certificates \| June 2016
Debt Instrument [Line Items]
Principal	$ 324
Final expected distribution date	2028-07
Stated interest rate	3.45%
Total debt recorded	$ 324
Proceeds received from issuance of debt	142
United Airlines, Inc. \| EETC
Debt Instrument [Line Items]
Principal	1,973
Total debt recorded	1,418
Proceeds received from issuance of debt	710
Remaining proceeds from issuance of debt to be received in future periods	$ 555

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

+ References

No definition available.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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Face (par) amount of debt instrument at time of issuance.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
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-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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