Aircraft Lease Assets (Details 2) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Aircraft Lease Assets (Details)
Gross minimum lease payments receivable	$ 1,900,000	$ 4,138,000
Less unearned interest	(10,000)	(88,000)
Allowance for doubtful accounts	(1,190,000)	(1,503,000)
Difference between minimum lease payments receivable and collateral value of leases	0	0
Finance leases receivable	$ 700,000	$ 2,547,000