Summary of Collateral Covenants and Cross Default Provisions (Detail)	12 Months Ended
	Dec. 31, 2014
Credit Agreement
Debt Instrument [Line Items]
Collateral, Covenants and Cross Default Provisions	Secured by certain of United's international route authorities, specified take-off and landing slots at certain airports and certain other assets. The Credit Agreement requires the Company to maintain at least $3.0 billion of unrestricted liquidity at all times, which includes unrestricted cash, short-term investments and any undrawn amounts under any revolving credit facility and to maintain a minimum ratio of appraised value of collateral to the outstanding obligations under the Credit Agreement of 1.67 to 1.0 at all times. The Credit Agreement contains covenants that, among other things, restrict the ability of UAL and its restricted subsidiaries (as defined in the Credit Agreement) to incur additional indebtedness and to pay dividends on or repurchase stock. The Credit Agreement contains events of default customary for this type of financing, including a cross default and cross acceleration provision to certain other material indebtedness of the Company.
United Air Lines 6% Notes Due 2026
Debt Instrument [Line Items]
Collateral, Covenants and Cross Default Provisions	The amended and restated indenture for these notes, which are unsecured, contains covenants that, among other things, restrict the ability of the Company and its restricted subsidiaries (as defined in the indenture) to incur additional indebtedness and pay dividends on or repurchase stock. These covenants cease to be in effect when the indenture covering the 6.375% Senior Notes due 2018 is discharged. The indenture contains events of default that are customary for similar financings.
United Air Lines 6% Notes Due 2028
Debt Instrument [Line Items]
Collateral, Covenants and Cross Default Provisions	The amended and restated indenture for these notes, which are unsecured, contains covenants that, among other things, restrict the ability of the Company and its restricted subsidiaries (as defined in the indenture) to incur additional indebtedness and pay dividends on or repurchase stock. These covenants cease to be in effect when the indenture covering the 6.375% Senior Notes due 2018 is discharged. The indenture contains events of default that are customary for similar financings.
6.375% Senior Notes due 2018
Debt Instrument [Line Items]
Collateral, Covenants and Cross Default Provisions	The indentures for these notes, which are unsecured, contain covenants that, among other things, restrict the ability of the Company and its restricted subsidiaries (as defined in the indenture) to incur additional indebtedness and pay dividends on or repurchase stock. The indentures contain events of default that are customary for similar financings.
Senior Notes 6% Due 2020
Debt Instrument [Line Items]
Collateral, Covenants and Cross Default Provisions	The indentures for these notes, which are unsecured, contain covenants that, among other things, restrict the ability of the Company and its restricted subsidiaries (as defined in the indenture) to incur additional indebtedness and pay dividends on or repurchase stock. The indentures contain events of default that are customary for similar financings.