Components of Accumulated Other Comprehensive Income (loss), Net of Tax (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2012 Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2013 Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2012 Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2013 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2012 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2013 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2012 Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2013 Other Accumulated Other Comprehensive Income	Jun. 30, 2013 Other Accumulated Other Comprehensive Income	Jun. 30, 2012 Other Accumulated Other Comprehensive Income	Mar. 31, 2012 Other Accumulated Other Comprehensive Income	Jun. 30, 2013 United Airlines, Inc.	Jun. 30, 2012 United Airlines, Inc.	Jun. 30, 2013 United Airlines, Inc.	Jun. 30, 2012 United Airlines, Inc.	Jun. 30, 2013 United Airlines, Inc. Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2012 United Airlines, Inc. Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2013 United Airlines, Inc. Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2012 United Airlines, Inc. Accumulated Defined Benefit Plans Adjustment	Jun. 30, 2013 United Airlines, Inc. Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2012 United Airlines, Inc. Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2013 United Airlines, Inc. Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2012 United Airlines, Inc. Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	Jun. 30, 2013 United Airlines, Inc. Other Accumulated Other Comprehensive Income	Jun. 30, 2012 United Airlines, Inc. Other Accumulated Other Comprehensive Income	Jun. 30, 2013 United Airlines, Inc. Other Accumulated Other Comprehensive Income	Jun. 30, 2012 United Airlines, Inc. Other Accumulated Other Comprehensive Income	Jun. 30, 2013 United Airlines, Inc. Income Tax Benefit Expense	Jun. 30, 2012 United Airlines, Inc. Income Tax Benefit Expense	Mar. 31, 2012 United Airlines, Inc. Income Tax Benefit Expense	Dec. 31, 2011 United Airlines, Inc. Income Tax Benefit Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (1,027)	$ (280)	$ (1,046)	$ (417)	$ (1,021)	$ (308)	$ (1,042)	$ (312)	$ (10)	$ 25	$ (10)	$ (99)	$ 4	$ 6	$ (6)	$ 3	$ (1,027)	$ (287)	$ (1,053)	$ (425)	$ (1,021)	$ (308)	$ (1,042)	$ (312)	$ (10)	$ 25	$ (10)	$ (99)	$ 4	$ 2	$ 5	$ (8)	$ (6)	$ (6)	$ (6)	$ (6)
Other comprehensive income (loss) before reclassifications	(10)	(262)	(21)	(160)					(19)	(262)	(28)	(169)	9	7	9		(10)	(263)	(20)	(160)					(19)	(262)	(28)	(169)	9	(1)	8	9
Actuarial gain due to curtailment and remeasurement	442		442		442		442										442		442		442		442
Amounts reclassified from accumulated other comprehensive income	26	43	56	78	17	5	38	9	9	38	18	69					26	43	62	78	17	5	38	9	9	38	18	69					6
Net current-period other comprehensive income (loss)	458	(219)	477	(82)	459	5	480	9	(10)	(224)	(10)	(100)	9	7	9		458	(220)	484	(82)	459	5	480	9	(10)	(224)	(10)	(100)	9	(1)	8	9	6
Ending Balance	$ (569)	$ (499)	$ (569)	$ (499)	$ (562)	$ (303)	$ (562)	$ (303)	$ (20)	$ (199)	$ (20)	$ (199)	$ 13	$ 13	$ 3	$ 3	$ (569)	$ (507)	$ (569)	$ (507)	$ (562)	$ (303)	$ (562)	$ (303)	$ (20)	$ (199)	$ (20)	$ (199)	$ 13	$ 1	$ 13	$ 1		$ (6)	$ (6)	$ (6)