Revenue - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Deferred Revenue Arrangement [Line Items]
Refundable tickets expiration period				1 year
Passenger revenue	$ 9,880	$ 9,151	[1]	$ 18,030	$ 16,804	[1]
Frequent flyer mileage program expiration period after member account inactivity				18 months
Frequent flyer mileage program period in which miles redeemed				2 years
Other operating revenue	583	584	[1]	$ 1,172	1,119	[1]
Chase and Other Partner Agreements
Deferred Revenue Arrangement [Line Items]
Other operating revenue	480	459		974	873
Deferred Revenue for Miles in Loyalty Program
Deferred Revenue Arrangement [Line Items]
Passenger revenue	2,700	$ 2,600		$ 2,200	2,200
Advance tickets expiration period				12 months
Deferred revenue, period to be recognized		12 months
Minimum
Deferred Revenue Arrangement [Line Items]
Frequent flyer mileage program expiration period				1 year
Maximum
Deferred Revenue Arrangement [Line Items]
Frequent flyer mileage program expiration period				8 years
Passenger Revenue
Deferred Revenue Arrangement [Line Items]
Ancillary fees	$ 555	$ 524		$ 1,052	$ 1,002

[1] Amounts adjusted due to the adoption of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) and Accounting Standards Update No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. See Note 1 to the financial statements contained in Part I, Item 1 of this report for additional information.