Revenue from Contracts with Customers - Disaggregates revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Revenue from Contracts with Customers
Leasing revenue	$ 56,014
Gain on sale of leased equipment	640	$ 983
Revenue	1,882
Total revenue	63,892	77,946
Spare parts and equipment sales
Revenue from Contracts with Customers
Revenue	6,286
Managed services
Revenue from Contracts with Customers
Revenue	921
Other revenue
Revenue from Contracts with Customers
Revenue	31
Operating Segments \| Leasing and Related Operations
Revenue from Contracts with Customers
Leasing revenue	56,014
Gain on sale of leased equipment	640	983
Total revenue	57,575	71,727
Operating Segments \| Leasing and Related Operations \| Managed services
Revenue from Contracts with Customers
Revenue	921
Operating Segments \| Spare Parts Sales
Revenue from Contracts with Customers
Total revenue	7,399	6,346
Operating Segments \| Spare Parts Sales \| Spare parts and equipment sales
Revenue from Contracts with Customers
Revenue	6,286
Operating Segments \| Spare Parts Sales \| Other revenue
Revenue from Contracts with Customers
Revenue	1,113
Eliminations
Revenue from Contracts with Customers
Total revenue	(1,082)	$ (127)
Eliminations \| Other revenue
Revenue from Contracts with Customers
Revenue	$ (1,082)

The net gain (loss) arising from the lessor's sale of assets held- or available-for-lease under contractual arrangements classified as operating leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68074852&loc=d3e41205-112714

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 40
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6455249&loc=d3e44908-112734

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 40
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=68074852&loc=d3e41188-112714

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The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7501430&loc=d3e39896-112707

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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