Net Investment in Finance Leases Net Investment in Finance Leases (Details) $ in Thousands	Feb. 29, 2020 USD ($) aircraft	Dec. 31, 2019 USD ($) aircraft
Receivables [Abstract]
Capital Leased Assets, Number of Units | aircraft	30	29
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Lease receivable	$ 166,060	$ 164,816
Unguaranteed residual value of flight equipment	266,750	254,580
Capital Leases Investment In Direct Financing And Sales Type Leases before Allowance	432,810	419,396
Financing Receivable, Allowance for Credit Loss, Current	(6,558)	0
Net investment in leases, net of allowance for credit losses of $6,558 and $0, respectively	426,252	$ 419,396
Receivable in Remainder of Fiscal Year	51,302
Receivable in Year Two	45,936
Receivable in Year Three	33,270
Receivable in Year Four	28,523
Receivable in Year Five	10,232
Thereafter	21,989
Total	191,252
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount	(166,060)
Difference between the Present Value and Undiscounted Sales Type and Direct Financing Lease Receivable	$ 25,192