Legal Proceedings - Additional Information (Detail) shares in Millions	1 Months Ended
	Jun. 30, 2015 Lawsuits	Sep. 30, 2017 shares
Long-term Purchase Commitment [Line Items]
Shares reserved for future issuance | shares		24.5
Number of putative class action lawsuits	100
American Airlines, Inc. [Member]
Long-term Purchase Commitment [Line Items]
Number of putative class action lawsuits	100