Special Charges (Credit) - Narrative (Details) employee in Thousands	1 Months Ended	3 Months Ended			9 Months Ended
	Jul. 31, 2020 employee	Sep. 30, 2020 USD ($) employee	Sep. 30, 2019 USD ($)	Mar. 31, 2017 USD ($) employee	Sep. 30, 2020 USD ($) employee	Sep. 30, 2019 USD ($)
Restructuring Cost and Reserve [Line Items]
Cash received under the Payroll Support Program		$ 5,100,000,000			$ 5,100,000,000
Cash received from grants		3,600,000,000			3,600,000,000
Cash received from the issuance of an unsecured loan		1,500,000,000			1,500,000,000
Cash received from the issuance of warrants					66,000,000
Portion of grant recognized as a credit to special charges due to COVID-19		1,494,000,000	$ 0		3,083,000,000	$ 0
Deferred credit		$ (453,000,000)			$ (453,000,000)
Number of employees notified of plans for workforce reduction | employee	36
Number of employee furloughs | employee		13			13
Number of employees subject to voluntary options | employee		9			9
Severance and benefit costs		$ 350,000,000	2,000,000		$ 413,000,000	14,000,000
Settlement losses		415,000,000	0		646,000,000	0
Nonoperating unrealized losses on investments			(21,000,000)		295,000,000	(72,000,000)
Nonoperating credit loss on BRW Term Loan and related guarantee		0	0		697,000,000	0
Charge for the early termination of several regional aircraft finance leases						6,000,000
Fair value adjustment for aircraft purchased off lease						8,000,000
Other miscellaneous impairments						8,000,000
Gain (loss) for the change in fair value of equity investments			25,000,000			77,000,000
Loss recorded for the change in fair value of certain derivative assets			4,000,000			5,000,000
Investments excluding AVH Derivative Assets
Restructuring Cost and Reserve [Line Items]
Nonoperating unrealized losses on investments		(15,000,000)			271,000,000
AVH Derivative Assets
Restructuring Cost and Reserve [Line Items]
Nonoperating unrealized losses on investments					24,000,000
Management
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs			$ 2,000,000			12,000,000
Voluntary Early-Out Program | International Brotherhood of Teamsters
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs						2,000,000
Number of technicians and related employees that elected to voluntarily separate from the Company | employee				1
Maximum severance payment per employee (up to)				$ 100,000
Term Loan Receivable | BRW
Restructuring Cost and Reserve [Line Items]
Nonoperating credit loss on BRW Term Loan and related guarantee					697,000,000
Routes
Restructuring Cost and Reserve [Line Items]
Impairment of intangible assets		0			130,000,000
Fair value of indefinite-lived intangible assets		1,100,000,000			$ 1,100,000,000
Aircraft Engines
Restructuring Cost and Reserve [Line Items]
Impairment for aircraft engines removed from operations						$ 47,000,000
Embedded Aircraft Lease
Restructuring Cost and Reserve [Line Items]
Impairment of right-of-use asset		$ 38,000,000