Leases Narrative (Details)	6 Months Ended
	Jun. 30, 2021 USD ($) aircraft aircraft_Engine
Lessee, Lease, Description [Line Items]
Number of aircraft held	164
Number of spare engines capitalized	16
Operating lease not yet commenced, amount | $	$ 2,200,000
Operating lease not yet commenced, amount, year one | $	$ 0
Aircraft
Lessee, Lease, Description [Line Items]
Number of capitalized aircraft or engine purchased off lease	33
A320 Family | Aircraft
Lessee, Lease, Description [Line Items]
Number of aircraft capitalized	105
Aircraft
Lessee, Lease, Description [Line Items]
Number of aircraft under sale-leaseback transactions	2
Number of previously leased aircraft or engine purchased off lease	4
Aircraft | A320 Family
Lessee, Lease, Description [Line Items]
Number of leased assets financed under operating leases	59
Aircraft | Minimum
Lessee, Lease, Description [Line Items]
Operating leases, term	8 years
Aircraft | Maximum
Lessee, Lease, Description [Line Items]
Operating leases, term	18 years
Other Leased Equipment and Property | Maximum
Lessee, Lease, Description [Line Items]
Operating leases, term	99 years
Spare Engines
Lessee, Lease, Description [Line Items]
Number of leased assets financed under operating leases | aircraft_Engine	8
Leased Computer And Office Equipment | Minimum
Lessee, Lease, Description [Line Items]
Finance leases, term	4 years
Leased Computer And Office Equipment | Maximum
Lessee, Lease, Description [Line Items]
Finance leases, term	5 years
Third Party Lessor
Lessee, Lease, Description [Line Items]
Number of delivered leased aircraft	5