Commitments and Contingencies - Additional Information (Detail)		6 Months Ended
	Feb. 17, 2017 Aircraft	Jun. 30, 2017 USD ($) Employee Aircraft
Commitments and Contingencies [Line Items]
Aggregate balance		$ 10,900,000,000
Tax-exempt special facilities revenue bonds
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure		1,900,000,000
Operating leases obligations		1,400,000,000
Capital leases obligations		432,000,000
Floating Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount		3,100,000,000
Fixed Rate Debt
Commitments and Contingencies [Line Items]
Debt instrument principal amount		75,000,000
Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Aggregate balance		3,100,000,000
Aircraft Mortgage Debt
Commitments and Contingencies [Line Items]
Guarantor obligations, maximum exposure		$ 163,000,000
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)		11 years
Maximum | Tax-exempt special facilities revenue bonds
Commitments and Contingencies [Line Items]
Debt instrument maturity year		2038
Maximum | Loans And Leases From Non U S Entities
Commitments and Contingencies [Line Items]
Debt instrument, remaining terms (years)		11 years
United Airlines, Inc.
Commitments and Contingencies [Line Items]
Debt instrument maturity year		2027
Debt instrument principal amount		$ 167,000,000
Number of employees | Employee		90,600
Percentage of employees represented by various U.S. labor organizations		80.00%
United Airlines, Inc. | EETC
Commitments and Contingencies [Line Items]
Remaining proceeds from issuance of debt to be received in future periods		$ 278,000,000
Debt instrument principal amount		$ 1,973,000,000
United Airlines, Inc. | Boeing 777-300ER Aircraft
Commitments and Contingencies [Line Items]
Number of additional aircraft ordered for future delivery | Aircraft		4
United Airlines, Inc. | Boeing 737 MAX 10s
Commitments and Contingencies [Line Items]
Number of aircraft to be converted | Aircraft		100
United Airlines, Inc. | Delivered in Second Half of Twenty Seventeen [Member] | Embraer E175 Aircraft
Commitments and Contingencies [Line Items]
Number of additional aircraft ordered for future delivery | Aircraft		8
United Airlines, Inc. | Capital Addition Purchase Commitments
Commitments and Contingencies [Line Items]
New aircraft, scheduled delivery date		2027
United Airlines, Inc. | Capital Addition Purchase Commitments | Boeing 737NG
Commitments and Contingencies [Line Items]
Number of aircraft expected to be delivered through the remainder of 2017 | Aircraft		4
United Airlines, Inc. | Capital Addition Purchase Commitments | B 787-9
Commitments and Contingencies [Line Items]
Number of aircraft expected to be delivered through the remainder of 2017 | Aircraft		1
United Airlines, Inc. | Capital Addition Purchase Commitments | Embraer E175 Aircraft
Commitments and Contingencies [Line Items]
Number of aircraft expected to be delivered through the remainder of 2017 | Aircraft		14
United Airlines, Inc. | Capital Addition Purchase Commitments | A319 aircraft
Commitments and Contingencies [Line Items]
Number of aircraft expected to be delivered through the remainder of 2017 | Aircraft		4
Air Wisconsin | Minimum | CRJ 200
Commitments and Contingencies [Line Items]
Number of aircraft to operate | Aircraft	50
Air Wisconsin | Maximum | CRJ 200
Commitments and Contingencies [Line Items]
Number of aircraft to operate | Aircraft	65