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Equipment Held for Operating Lease and Notes Receivable - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 engine	Jun. 30, 2021 aircraft.	Jun. 30, 2021 marineVessel	Dec. 31, 2020 USD ($)	Dec. 31, 2020 engine	Dec. 31, 2020 aircraft.	Dec. 31, 2020 marineVessel
Lessor, Lease, Description [Line Items]
Equipment held for operating lease, property, equipment, and furnishings, less accumulated depreciation	$ 31,148		$ 31,148					$ 31,753
Notes receivable	195,645		195,645					158,708
Number of leased assets					300	8	1		291	8	1
Note Receivable
Lessor, Lease, Description [Line Items]
Interest income	$ 3,600	$ 2,700	6,500	$ 3,700
Minimum \| Note Receivable
Lessor, Lease, Description [Line Items]
Note receivable, effective interest rate	6.30%	6.30%
Maximum \| Note Receivable
Lessor, Lease, Description [Line Items]
Note receivable, effective interest rate	12.20%	13.70%
Equipment Held For Operating Lease
Lessor, Lease, Description [Line Items]
Equipment held for operating lease, property, equipment, and furnishings, less accumulated depreciation	$ 1,889,908		$ 1,889,908					$ 1,886,613