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Summary of Significant Accounting Policies (Inventory) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) compressor	Dec. 31, 2016 USD ($) compressor
Inventory [Line Items]
Inventory valuation reserves, deductions	$ 15	$ 15
Available-for-sale or rental, compressor units | compressor	7	7
Raw materials -current	$ 22,813	$ 15,877
Long-Term Inventory, net of allowance for obsolescence of $15 and $15, respectively	2,829	2,488
Finished Goods	1,022	2,558
Work in process	2,389	2,998
Inventory	29,053	23,921
Rental Equipment [Member]
Inventory [Line Items]
Work in process	$ 6,400	$ 1,900

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(d))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(6)(a)(4))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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