Revenue Recognition - Disaggregation Of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Operating revenue	$ 60,004	$ 712,189	$ 619,148	$ 1,368,940
Passenger revenue, excluding frequent flyer
Disaggregation of Revenue [Line Items]
Operating revenue	26,169	613,574	500,304	1,181,429
Frequent flyer revenue, transportation component
Disaggregation of Revenue [Line Items]
Operating revenue	3,593	39,849	32,927	73,298
Passenger Revenue
Disaggregation of Revenue [Line Items]
Operating revenue	29,762	653,423	533,231	1,254,727
Other revenue (e.g., cargo and other miscellaneous)
Disaggregation of Revenue [Line Items]
Operating revenue	17,436	36,571	51,619	72,802
Frequent flyer revenue, marketing and brand component
Disaggregation of Revenue [Line Items]
Operating revenue	12,806	22,195	34,298	41,411
Other Revenue
Disaggregation of Revenue [Line Items]
Operating revenue	30,242	58,766	85,917	114,213
Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	55,106	531,725	457,120	1,009,245
Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	$ 4,898	$ 180,464	$ 162,028	$ 359,695