Fair Value Measurements and Other Investments - Other Investments (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment [Line Items]
Regional expenses			$ 6,546	$ 6,044	$ 5,983
Regional Carrier [Member]
Investment [Line Items]
Regional expenses			$ 6,546	6,044	5,983
Republic Airways Holdings, Inc. [Member]
Investment [Line Items]
Equity method investment, ownership percentage			25.00%
Republic Airways Holdings, Inc. [Member] | Regional Carrier [Member]
Investment [Line Items]
Regional expenses		$ 544
China Southern Airlines Company Limited [Member]
Investment [Line Items]
Cost method investments, ownership percentage	2.70%
Cost method investments	$ 203
Cost method investments, required holding period	3 years
American Airlines, Inc. [Member]
Investment [Line Items]
Regional expenses			$ 6,572	6,009	5,952
American Airlines, Inc. [Member] | Regional Carrier [Member]
Investment [Line Items]
Regional expenses			$ 6,572	$ 6,009	$ 5,952
American Airlines, Inc. [Member] | Republic Airways Holdings, Inc. [Member]
Investment [Line Items]
Equity method investment, ownership percentage			25.00%
American Airlines, Inc. [Member] | Republic Airways Holdings, Inc. [Member] | Regional Carrier [Member]
Investment [Line Items]
Regional expenses		$ 544
American Airlines, Inc. [Member] | China Southern Airlines Company Limited [Member]
Investment [Line Items]
Cost method investments, ownership percentage	2.70%
Cost method investments	$ 203
Cost method investments, required holding period	3 years