Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents	$ 4,143	$ 4,770
Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	762	715
Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	511	537
CDARS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	358	367
Auction Rate Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	115	116
Other Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	75	38
EETC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
EETC	62	63
Fuel Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fuel derivative asset (liability), net	(23)	46
Foreign Currency Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency derivatives, net	1
Restricted Cash
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	435	447
Level 1 | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents	4,143	4,770
Level 1 | Restricted Cash
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	435	447
Level 2 | Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	762	715
Level 2 | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	511	537
Level 2 | CDARS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	358	367
Level 2 | Other Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	75	38
Level 2 | Fuel Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fuel derivative asset (liability), net	(23)	46
Level 2 | Foreign Currency Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency derivatives, net	1
Level 3 | Auction Rate Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	115	116
Level 3 | EETC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
EETC	62	63
United Airlines, Inc. | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents	4,137	4,765
United Airlines, Inc. | Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	762	715
United Airlines, Inc. | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	511	537
United Airlines, Inc. | CDARS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	358	367
United Airlines, Inc. | Auction Rate Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	115	116
United Airlines, Inc. | Other Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	75	38
United Airlines, Inc. | EETC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
EETC	62	63
United Airlines, Inc. | Fuel Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fuel derivative asset (liability), net	(23)	46
United Airlines, Inc. | Foreign Currency Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency derivatives, net	1
United Airlines, Inc. | Restricted Cash
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	435	447
United Airlines, Inc. | Convertible Debt Derivative Asset
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Convertible debt derivative asset	395	268
United Airlines, Inc. | Convertible Debt Option Liability
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Convertible debt option liability	(199)	(128)
United Airlines, Inc. | Level 1 | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash and cash equivalents	4,137	4,765
United Airlines, Inc. | Level 1 | Restricted Cash
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Restricted cash	435	447
United Airlines, Inc. | Level 2 | Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	762	715
United Airlines, Inc. | Level 2 | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	511	537
United Airlines, Inc. | Level 2 | CDARS
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	358	367
United Airlines, Inc. | Level 2 | Other Short-term Investments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	75	38
United Airlines, Inc. | Level 2 | Fuel Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fuel derivative asset (liability), net	(23)	46
United Airlines, Inc. | Level 2 | Foreign Currency Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign currency derivatives, net	1
United Airlines, Inc. | Level 3 | Auction Rate Securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments	115	116
United Airlines, Inc. | Level 3 | EETC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
EETC	62	63
United Airlines, Inc. | Level 3 | Convertible Debt Derivative Asset
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Convertible debt derivative asset	395	268
United Airlines, Inc. | Level 3 | Convertible Debt Option Liability
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Convertible debt option liability	$ (199)	$ (128)