Special Charges - Additional Information (Detail)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($) Aircraft	Mar. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) Attendant
Special Charges [Line Items]
Severance and benefits	$ 25,000,000	$ 38,000,000		$ 75,000,000	$ 52,000,000
Impairment of assets and other special gains and losses	16,000,000			12,000,000
Loss on extinguishment of debt and other, net	128,000,000			134,000,000	21,000,000
Costs associated with aircraft		$ 66,000,000			66,000,000
Number of leased aircraft | Aircraft		21
Lease expiry year		2018
Losses on sales of aircraft and other assets and other special losses, net	(16,000,000)	$ (48,000,000)		(12,000,000)	(52,000,000)
Venezuela local currency loss			$ 21,000,000
Accrual severance and benefit	$ 104,000,000	$ 82,000,000		$ 104,000,000	82,000,000
Severance-related accrual expected payment date				2015
Weighted Average | Cleveland
Special Charges [Line Items]
Percentage of flight reductions in average daily departures from Cleveland		60.00%
Boeing 737-300 and 737-500 fleets
Special Charges [Line Items]
Impairment of assets held for disposal					33,000,000
Losses on sales of aircraft and other assets and other special losses, net					$ (19,000,000)
Voluntary early out program
Special Charges [Line Items]
Number of positions eliminated | Attendant						2,500
Voluntary early out program | Maximum
Special Charges [Line Items]
Severance payment per participant						$ 100,000
Scenario Forecast | Voluntary early out program
Special Charges [Line Items]
Severance and benefits				$ 25,000,000