Supplemental Disclosures of Cash Flow Information and Non-Cash Investing and Financing Activities (Parenthetical) (Detail)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
UAL 6% Senior Convertible Notes
Cash Flow Supplemental Disclosures [Line Items]
Debt instrument stated interest rate	6.00%	6.00%	6.00%
UAL 6% Senior Convertible Notes | United Airlines, Inc.
Cash Flow Supplemental Disclosures [Line Items]
Debt instrument stated interest rate	6.00%	6.00%	6.00%
UAL 4.5% Senior Convertible Notes
Cash Flow Supplemental Disclosures [Line Items]
Debt instrument stated interest rate	4.50%
UAL 4.5% Senior Convertible Notes | United Airlines, Inc.
Cash Flow Supplemental Disclosures [Line Items]
Debt instrument stated interest rate	4.50%
UAL 8% Contingent Senior Notes
Cash Flow Supplemental Disclosures [Line Items]
Debt instrument stated interest rate			8.00%
UAL 8% Contingent Senior Notes | United Airlines, Inc.
Cash Flow Supplemental Disclosures [Line Items]
Debt instrument stated interest rate			8.00%