Property and Equipment (Schedule of Property and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross		$ 3,297,442	$ 3,189,643
Accumulated depreciation		(1,310,360)	(1,249,867)
Property and equipment, net	$ 1,987,082	1,987,082	1,939,776
Flight Equipment [Member]
Property, Plant and Equipment [Line Items]
Operating Leases, Future Minimum Payments Receivable, Current	222,400	192,300
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross		2,985,850	2,856,142
Operating Leases, Future Minimum Payments Receivable, in Two Years	195,500	212,800
Operating Leases, Future Minimum Payments Receivable, in Three Years	150,500	168,300
Operating Leases, Future Minimum Payments Receivable, in Four Years	99,800	117,600
Operating Leases, Future Minimum Payments Receivable, in Five Years	$ 90,700	105,400
Ground equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross		67,332	65,857
facilities, leasehold improvements and office equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross		37,283	36,193
Construction in Progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property and equipment, gross		$ 206,977	$ 231,451