Commitments and Contingencies - Additional Information (Detail) Employee in Thousands	1 Months Ended					12 Months Ended
	Dec. 31, 2016 USD ($) Employee	Aug. 31, 2016	Apr. 30, 2016 Contract	Mar. 31, 2016	Jan. 31, 2016	Dec. 31, 2016 USD ($) Employee Contract Option	Dec. 31, 2014 USD ($)
Commitments and Contingencies [Line Items]
Debt instrument principal amount							$ 248,000,000
Number of call options to purchase regional jet aircraft | Option						223
Int'1 Brotherhood of Teamsters
Commitments and Contingencies [Line Items]
Service contract extended year	2022
Contract period	6 years
Air Line Pilots Association International
Commitments and Contingencies [Line Items]
Service contract extended year					Jan. 31, 2019
Professional Airline Flight Control Association
Commitments and Contingencies [Line Items]
Service contract extended year				2021
Int'1 Association of Machinists
Commitments and Contingencies [Line Items]
Service contract extended year			2021			2021
Number of new contracts extended | Contract			7			7
United And The Association Of Flight Attendants
Commitments and Contingencies [Line Items]
Contract period		5 years
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	$ 168,000,000					$ 168,000,000
Floating Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount	2,600,000,000					2,600,000,000
Fixed Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount	90,000,000					90,000,000
Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Debt instrument principal amount	2,600,000,000					2,600,000,000
Tax-exempt special facilities revenue bonds
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	1,900,000,000					1,900,000,000
Operating leases obligations	1,400,000,000					1,400,000,000
Capital leases obligations	400,000,000					400,000,000
Tax-exempt special facilities revenue bonds | Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure	234,000,000					234,000,000
Contingent liabilities based on participation	1,500,000,000					$ 1,500,000,000
Maximum
Commitments and Contingencies [Line Items]
Debt instrument, remaining terms (years)						12 years
Maximum | Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Debt instrument, remaining terms (years)						12 years
Maximum | Tax-exempt special facilities revenue bonds
Commitments and Contingencies [Line Items]
Debt instrument maturity year						2038
Maximum | Tax-exempt special facilities revenue bonds | Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Debt instrument maturity year						2049
Minimum | Tax-exempt special facilities revenue bonds
Commitments and Contingencies [Line Items]
Debt instrument maturity year						2017
Minimum | Tax-exempt special facilities revenue bonds | Indirect Guarantee of Indebtedness
Commitments and Contingencies [Line Items]
Debt instrument maturity year						2017
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Borrowed principal amount	$ 369,000,000					$ 369,000,000
Number of employees | Employee	88					88
Percentage of employees represented by various U.S. labor organizations						80.00%
United Airlines, Inc. | EETC
Commitments and Contingencies [Line Items]
Borrowed principal amount	$ 1,973,000,000					$ 1,973,000,000
Debt instrument principal amount	$ 708,000,000					$ 708,000,000
United Airlines, Inc. | Maximum
Commitments and Contingencies [Line Items]
Debt instrument maturity year						2028
United Airlines, Inc. | Minimum
Commitments and Contingencies [Line Items]
Debt instrument maturity year						2026
Capital Addition Purchase Commitments | United Airlines, Inc. | Maximum
Commitments and Contingencies [Line Items]
New aircraft, scheduled delivery date						2027
Capital Addition Purchase Commitments | United Airlines, Inc. | Minimum
Commitments and Contingencies [Line Items]
New aircraft, scheduled delivery date						2017