Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 138,529	$ 1,012,956	$ 909,610	$ 1,868,752
Refunds issued	77,400		121,000
Air traffic liability	452,023		$ 452,023		$ 315,408
Minimum
Disaggregation of Revenue [Line Items]
Credit shell term expiration			60 days
Maximum
Disaggregation of Revenue [Line Items]
Credit shell term expiration			12 months
DOT—Domestic
Disaggregation of Revenue [Line Items]
Total operating revenues	134,373	890,388	$ 832,293	1,644,502
DOT—Latin America
Disaggregation of Revenue [Line Items]
Total operating revenues	4,156	122,568	77,317	224,250
Passenger
Disaggregation of Revenue [Line Items]
Total operating revenues	130,817	994,430	884,367	1,832,495
Fare
Disaggregation of Revenue [Line Items]
Total operating revenues	63,769	515,696	385,216	932,041
Non-fare
Disaggregation of Revenue [Line Items]
Total operating revenues	67,048	478,734	499,151	900,454
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 7,712	$ 18,526	$ 25,243	$ 36,257