Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 3,424	$ 3,220
Restricted cash	351	395
United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	3,418	3,214
Restricted cash	351	395
Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	910	694
Asset-backed Securities | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	910	694
Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	790	685
Corporate Debt | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	790	685
CDARS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	308	301
CDARS | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	308	301
Auction Rate Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	26	105
Auction Rate Securities | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	26	105
U.S. Government And Agency Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	40	38
U.S. Government And Agency Notes | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	40	38
Other Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	298	78
Other Fixed Income Securities | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	298	78
Fuel Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	116	104
Fuel Derivatives, Net | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	116	104
EETC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
EETC	59	61
EETC | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
EETC	59	61
Foreign Currency Derivative Asset (Liability), Net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	(1)	1
Foreign Currency Derivative Asset (Liability), Net | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	(1)	1
Convertible Debt Derivative Asset | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt derivative asset	449	480
Convertible Debt Option Liability | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt option liability	(263)	(270)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	3,424	3,220
Restricted cash	351	395
Level 1 | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	3,418	3,214
Restricted cash	351	395
Level 2 | Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	910	694
Level 2 | Asset-backed Securities | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	910	694
Level 2 | Corporate Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	790	685
Level 2 | Corporate Debt | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	790	685
Level 2 | CDARS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	308	301
Level 2 | CDARS | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	308	301
Level 2 | U.S. Government And Agency Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	40	38
Level 2 | U.S. Government And Agency Notes | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	40	38
Level 2 | Other Fixed Income Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	298	78
Level 2 | Other Fixed Income Securities | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	298	78
Level 2 | Fuel Derivatives, Net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	116	104
Level 2 | Fuel Derivatives, Net | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	116	104
Level 2 | Foreign Currency Derivative Asset (Liability), Net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	(1)	1
Level 2 | Foreign Currency Derivative Asset (Liability), Net | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, net	(1)	1
Level 3 | Auction Rate Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	26	105
Level 3 | Auction Rate Securities | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	26	105
Level 3 | EETC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
EETC	59	61
Level 3 | EETC | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
EETC	59	61
Level 3 | Convertible Debt Derivative Asset | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt derivative asset	449	480
Level 3 | Convertible Debt Option Liability | United Airlines, Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt option liability	$ (263)	$ (270)