Commitments and Contingencies - Additional Information (Detail)	1 Months Ended					9 Months Ended
	Oct. 17, 2016	Sep. 30, 2016 USD ($) Employee Aircraft	Aug. 31, 2016	Mar. 31, 2016 Contract	Jan. 31, 2016	Sep. 30, 2016 USD ($) Employee Aircraft Contract
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure		$ 171,000,000				$ 171,000,000
Floating Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount		2,500,000,000				2,500,000,000
Fixed Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount		97,000,000				97,000,000
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		$ 376,000,000				$ 376,000,000
Minimum | Tax-exempt special facilities revenue bonds
Commitments and Contingencies [Line Items]
Debt instrument maturity year						2017
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
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
Int'1 Brotherhood of Teamsters
Commitments and Contingencies [Line Items]
Contract period		6 years
Metropolitan Washington Airports Authority | Subsequent Event
Commitments and Contingencies [Line Items]
Lease extension term	7 years
Operating lease expiration year	2024
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Borrowed principal amount		$ 272,000,000				$ 272,000,000
Debt instrument maturity year						2028
Number of employees | Employee		87,500				87,500
Percentage of employees represented by various U.S. labor organizations						80.00%
United Airlines, Inc. | EETC
Commitments and Contingencies [Line Items]
Borrowed principal amount		$ 1,700,000,000				$ 1,700,000,000
Debt instrument principal amount		$ 321,000,000				$ 321,000,000
Capital Addition Purchase Commitments | United Airlines, Inc.
Commitments and Contingencies [Line Items]
New aircraft, scheduled delivery date						2024
Capital Addition Purchase Commitments | United Airlines, Inc. | Boeing 737NG
Commitments and Contingencies [Line Items]
Number of aircraft expected to be delivered in the remainder of 2016 | Aircraft		7				7
Capital Addition Purchase Commitments | United Airlines, Inc. | Boeing 777-300ER Aircraft
Commitments and Contingencies [Line Items]
Number of aircraft expected to be delivered in the remainder of 2016 | Aircraft		1				1