Special Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Special charge related to wind-down	$ 63	$ 18
Nonoperating credit loss on BRW Term Loan and related guarantee	697	0
Nonoperating unrealized losses on investments	319	(17)
Loss recorded for the change in fair value of certain derivative assets	24
Fair value adjustment for aircraft purchased off lease		8
Severance and benefit costs	0	6
Gain for the change in fair value of certain derivative assets		3
Azul
Restructuring Cost and Reserve [Line Items]
Gain (loss) for the change in fair value of equity investments	(293)	14
Management
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		4
Trans States Airlines
Restructuring Cost and Reserve [Line Items]
Special charge related to wind-down	10
Transition of Fleet Types within Other Regional Carrier Contracts
Restructuring Cost and Reserve [Line Items]
Special charges	3
Voluntary Early-Out Program \| International Brotherhood of Teamsters
Restructuring Cost and Reserve [Line Items]
Severance and benefit costs		$ 2
Term Loan Receivable \| BRW
Restructuring Cost and Reserve [Line Items]
Nonoperating credit loss on BRW Term Loan and related guarantee	697
Routes
Restructuring Cost and Reserve [Line Items]
Fair value of indefinite-lived intangible assets	1,100
Impairment of intangible assets	$ 50

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