Legal Proceedings (Details) shares in Millions, $ in Millions			1 Months Ended	9 Months Ended
	Feb. 12, 2019 shares	Jun. 15, 2018 USD ($) lawsuit	Aug. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)
Long-term Purchase Commitment [Line Items]
Shares distributed from Disputed Claims Reserve (in shares) | shares	17.3
Shares reserved for future issuance (in shares) | shares	7.0
American Airlines, Inc. [Member]
Long-term Purchase Commitment [Line Items]
Number of putative class action lawsuits | lawsuit		100
Preliminary settlement amount | $		$ 45
Payments for legal settlements | $			$ 22	$ 22