Net Investment in Finance Leases Net Investment in Finance Leases (Details) $ in Thousands	Mar. 31, 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	$ 160,315	$ 164,816
Unguaranteed residual value of flight equipment	270,014	254,580
Capital Leases Investment In Direct Financing And Sales Type Leases before Allowance	430,329	419,396
Financing Receivable, Allowance for Credit Loss, Current	(9,865)	0
Net investment in leases, net of allowance for credit losses of $9,865 and $0, respectively	420,464	$ 419,396
Receivable in Remainder of Fiscal Year	46,034
Receivable in Year Two	44,415
Receivable in Year Three	33,270
Receivable in Year Four	28,523
Receivable in Year Five	10,232
Thereafter	21,989
Total	184,463
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount	(160,315)
Difference between the Present Value and Undiscounted Sales Type and Direct Financing Lease Receivable	$ 24,148