Revenue - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Deferred Revenue Arrangement [Line Items]
Passenger revenue	$ 8,149	$ 7,653	[1]
Frequent flyer mileage program expiration period after member account inactivity	18 months
Frequent flyer mileage program period in which miles redeemed	4 years
Other operating revenue	$ 590	535	[1]
Costs associated with non-travel miles redeemed	28	28
Chase and Other Partner Agreements
Deferred Revenue Arrangement [Line Items]
Other operating revenue	482	403
Deferred Revenue for Miles in Loyalty Program
Deferred Revenue Arrangement [Line Items]
Passenger revenue	$ 1,900	1,900
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	$ 497	$ 478

[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.