Fair Value Measurements and Other Investments - Other Investments (Details) $ in Millions	3 Months Ended
	Sep. 30, 2017 USD ($)
Republic Airways Holdings, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	25.00%
China Southern Airlines Company Limited [Member]
Schedule of Equity Method Investments [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] | Republic Airways Holdings, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	25.00%
American Airlines, Inc. [Member] | China Southern Airlines Company Limited [Member]
Schedule of Equity Method Investments [Line Items]
Cost method investments, ownership percentage	2.70%
Cost method investments	$ 203
Cost method investments, required holding period	3 years