Carrying Values and Estimated Fair Values of Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 11,437
Carrying (Reported) Amount, Fair Value Disclosure
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	11,276	11,539
Estimate of Fair Value, Fair Value Disclosure
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	12,536	12,695
Estimate of Fair Value, Fair Value Disclosure | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	8,684	8,829
Estimate of Fair Value, Fair Value Disclosure | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,852	3,866
United Airlines, Inc.
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	11,379
United Airlines, Inc. | Carrying (Reported) Amount, Fair Value Disclosure
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	11,174	11,388
United Airlines, Inc. | Estimate of Fair Value, Fair Value Disclosure
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	12,234	12,249
United Airlines, Inc. | Estimate of Fair Value, Fair Value Disclosure | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	8,382	8,383
United Airlines, Inc. | Estimate of Fair Value, Fair Value Disclosure | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 3,852	$ 3,866