Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Depreciable Lives Used for the Principal Depreciable Asset Classifications and Components of Depreciation and Amortization

The depreciable lives used for the principal depreciable asset classifications are:

	Estimated Useful Life
Aircraft, engines and flight simulators	25
Spare rotables and flight assemblies	7 to 25 years
Other equipment and vehicles	5 to 7 years
Internal use software	3 to 10 years
Finance leases	Lease term or estimated useful life of the asset
Leasehold improvements	Lesser of lease term or estimated useful life of the improvement
Buildings	Lesser of lease term or 30 years

The following table illustrates the components of depreciation and amortization expense:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Depreciation	$	193,079	$	179,470	$	155,326
Amortization of heavy maintenance	91,929		88,927		63,364
Amortization of capitalized software	12,203		10,191		6,574
Total depreciation and amortization	$	297,211	$	278,588	$	225,264

Primary Components of Non-fare Revenue and the Revenue Recognition Method Utilized for Each Service or Product

The following table summarizes the primary components of the Company's non-fare revenue and the revenue recognition method utilized for each service or product:

		Year Ended December 31,
Non-fare revenue	Recognition method	2021		2020		2019
		(in thousands)
Baggage	Time of departure	$	663,228	$	404,896	$	734,243
Passenger usage fee	Time of departure	610,762		358,561		669,177
Advance seat selection	Time of departure	215,682		125,213		228,876
Other	Varies	263,203		120,638		238,454
Non-fare revenue		$	1,752,875	$	1,009,308	$	1,870,750

Total Cash Proceeds Received from the Sale of Mileage Credit

The following table illustrates total cash proceeds received from the sale of points and the portion of such proceeds recognized in non-ticket revenue immediately as marketing component:

	Consideration received from credit card loyalty programs		Portion of proceeds recognized immediately as marketing component
Year Ended	(in thousands)
December 31, 2021	$	48,035	$	23,681
December 31, 2020	33,201		25,918
December 31, 2019	48,136		37,151

Aircraft Maintenance Expense

The table below summarizes the components of the Company’s maintenance cost:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Flight hour-based maintenance expense	$	81,591	$	52,092	$	78,253
Non-flight hour-based maintenance expense	77,911		59,135		65,322
Total maintenance, materials and repairs	$	159,502	$	111,227	$	143,575