Special Charges - Additional Information (Detail)	3 Months Ended				9 Months Ended
	Sep. 30, 2017 USD ($)	Mar. 31, 2017 USD ($) Technician	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($) plan
Special Charges [Line Items]
Severance and benefits costs	$ 23,000,000		$ 13,000,000		$ 101,000,000	$ 27,000,000
Severance and benefits costs net of tax			8,000,000			17,000,000
Impairment of assets	15,000,000				15,000,000	412,000,000
Labor agreement costs			14,000,000			$ 124,000,000
Lease maturity year						2029
Cleveland airport lease restructuring						$ 74,000,000
Cleveland airport lease restructuring, net of taxes						47,000,000
Accrual severance and benefit	31,000,000		34,000,000		$ 31,000,000	34,000,000
Severance-related accrual expected payment date					2019
Accrual for permanently grounded aircraft	28,000,000		41,000,000		$ 28,000,000	41,000,000
Grounded aircraft related accrual expected payment date					2025
Postretirement Medical Plan | Flight Attendant Postretirement Medical Plan
Special Charges [Line Items]
Curtailment gain recognition of prior service credit						47,000,000
Curtailment gain recognition of prior service credit,net of tax						$ 30,000,000
Number of plans amended | plan						2
Newark Liberty International Airport
Special Charges [Line Items]
Impairment of indefinite-lived intangible assets				$ 412,000,000
Impairment of indefinite-lived intangible assets, net of tax benefits				$ 264,000,000
International Brotherhood of Teamsters
Special Charges [Line Items]
Severance and benefits costs	16,000,000				$ 73,000,000
Severance and benefits costs net of tax	10,000,000				47,000,000
Int'l Association of Machinists
Special Charges [Line Items]
Labor agreement costs			61,000,000			$ 171,000,000
Labor agreement costs net of tax			$ 39,000,000			$ 109,000,000
Voluntary early out program | International Brotherhood of Teamsters
Special Charges [Line Items]
Number of positions eliminated | Technician		1,000
Voluntary early out program | International Brotherhood of Teamsters | Maximum
Special Charges [Line Items]
Severance payment per participant		$ 100,000
Management Reorganization Initiative
Special Charges [Line Items]
Severance and benefits costs	7,000,000				28,000,000
Severance and benefits costs net of tax	5,000,000				$ 18,000,000
Maintenance Service Agreement
Special Charges [Line Items]
Impairment of assets	15,000,000
Impairment of assets net of tax	$ 10,000,000