Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues		$ 38,454		$ 84,849
(Loss) gain on sale of leased equipment	$ 0	(700)	$ 0	1,367
Total revenue	66,472	74,983	127,597	156,592
Lease rent revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	32,431	38,454	63,951	84,849
Maintenance reserve revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	17,278	29,986	37,090	50,514
Spare parts and equipment sales
Revenue from Contracts with Customers
Other sales and revenues	3,569	2,855	8,135	11,960
Managed services
Revenue from Contracts with Customers
Other sales and revenues	3,247	1,631	5,515	4,125
Asset transition fee
Revenue from Contracts with Customers
Other sales and revenues	6,256	0	6,256	0
Other revenue
Revenue from Contracts with Customers
Other sales and revenues	3,691	2,757	6,650	3,777
Operating Segments | Leasing and Related Operations
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues		38,454		84,849
(Loss) gain on sale of leased equipment		(700)		1,367
Total revenue	62,965	72,229	119,588	145,953
Operating Segments | Leasing and Related Operations | Lease rent revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	32,431	38,454	63,951	84,849
Operating Segments | Leasing and Related Operations | Maintenance reserve revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	17,278	29,986	37,090	50,514
Operating Segments | Leasing and Related Operations | Spare parts and equipment sales
Revenue from Contracts with Customers
Other sales and revenues	84	102	169	1,327
Operating Segments | Leasing and Related Operations | Managed services
Revenue from Contracts with Customers
Other sales and revenues	3,247	1,631	5,515	4,125
Operating Segments | Leasing and Related Operations | Asset transition fee
Revenue from Contracts with Customers
Other sales and revenues	6,256		6,256
Operating Segments | Leasing and Related Operations | Other revenue
Revenue from Contracts with Customers
Other sales and revenues	3,669	2,756	6,607	3,771
Operating Segments | Spare Parts Sales
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues		0		0
(Loss) gain on sale of leased equipment		0		0
Total revenue	3,416	2,781	8,063	10,900
Operating Segments | Spare Parts Sales | Lease rent revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	0	0	0	0
Operating Segments | Spare Parts Sales | Maintenance reserve revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	0	0	0	0
Operating Segments | Spare Parts Sales | Spare parts and equipment sales
Revenue from Contracts with Customers
Other sales and revenues	3,375	2,753	7,966	10,633
Operating Segments | Spare Parts Sales | Managed services
Revenue from Contracts with Customers
Other sales and revenues	0	0	0	0
Operating Segments | Spare Parts Sales | Asset transition fee
Revenue from Contracts with Customers
Other sales and revenues	0		0
Operating Segments | Spare Parts Sales | Other revenue
Revenue from Contracts with Customers
Other sales and revenues	41	28	97	267
Eliminations
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues		0		0
(Loss) gain on sale of leased equipment		0		0
Total revenue	91	(27)	(54)	(261)
Eliminations | Lease rent revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	0	0	0	0
Eliminations | Maintenance reserve revenue
Revenue from Contracts with Customers
Lease rent and maintenance reserve revenues	0	0	0	0
Eliminations | Spare parts and equipment sales
Revenue from Contracts with Customers
Other sales and revenues	110	0	0	0
Eliminations | Managed services
Revenue from Contracts with Customers
Other sales and revenues	0	0	0	0
Eliminations | Asset transition fee
Revenue from Contracts with Customers
Other sales and revenues	0		0
Eliminations | Other revenue
Revenue from Contracts with Customers
Other sales and revenues	$ (19)	$ (27)	$ (54)	$ (261)