Fair Value Measurements (Details Textual)		3 Months Ended		6 Months Ended
	Feb. 29, 2020 USD ($) Aircraft	Jun. 30, 2020 USD ($) Aircraft	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Aircraft Lessee	Jun. 30, 2019 USD ($)	Aug. 01, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Lease Income, Current		$ 61,209,000		$ 61,209,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net				0
Impairment of flight equipment		280,088,000	$ 7,404,000	342,745,000	$ 7,404,000
Maintenance revenue, security deposits and advanced lease rentals recognized into income				$ 136,236,000
Number of Aircraft Impaired | Aircraft				20
Number Of Customers Entering Bankruptcy | Lessee				6
South African Airways [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft	4
Maintenance revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		72,168,000	$ 26,567,000	$ 118,720,000	$ 42,968,000
Maintenance revenue | South African Airways [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 38,804,000
Lease Rental Revenue | South African Airways [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,863,000
security deposit [Member] | South African Airways [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	8,740,000
Transactional [Member] | South African Airways [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Tangible Asset Impairment Charges	$ 62,657,000
Fleet Review [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Tangible Asset Impairment Charges		43,040,000
Subsequent Event
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Lease Income, Current						$ 99,000,000
Lease expirations and early lease terminations [Member] | Maintenance revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		69,995,000
Lease expirations and early lease terminations [Member] | security deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 12,834,000
Lease expirations and early lease terminations [Member] | Transactional [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft		11
Tangible Asset Impairment Charges		$ 77,298,000
Lessee bankruptcy [Member] | Transactional [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired		3
Tangible Asset Impairment Charges		$ 159,750,000
Narrow-body [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft				11
Narrow-body [Member] | Fleet Review [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft		1
Narrow-body [Member] | Lease expiration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft		1
Narrow-body [Member] | Early lease termination [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft		9
Wide-body [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft				9
Wide-body [Member] | Fleet Review [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft		1
Wide-body [Member] | Lease expiration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft		1