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Rental Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Subject to or Available for Operating Lease [Line Items]
Depreciation	$ 21,147	$ 21,641	$ 22,605
2018	6,494
2019	976
2020	543
2021	542
2022	542
Total	$ 9,097
Minimum
Property Subject to or Available for Operating Lease [Line Items]
Rental arrangements, original term	6 months
Maximum
Property Subject to or Available for Operating Lease [Line Items]
Rental arrangements, original term	24 months
Rental Equipment
Property Subject to or Available for Operating Lease [Line Items]
Depreciation	$ 20,000	$ 20,200	$ 21,000

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- Definition

Operating Leases of Lessor, Original Term

+ References

No definition available.

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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Future minimum rental payments in aggregate as of the balance sheet date under operating leases.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
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- Definition

Future rental payments receivable within one year of the balance sheet date under an operating lease.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
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Future rental payments receivable within the fifth year from the balance sheet date under an operating lease.

+ References

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-Publisher FASB
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- Definition

Future rental payments receivable within the fourth year from the balance sheet date under an operating lease.

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-Publisher FASB
-Name Accounting Standards Codification
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Future rental payments receivable within the third year from the balance sheet date under an operating lease.

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Future rental payments receivable within the second year from the balance sheet date under an operating lease.

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