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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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- Definition 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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 5.BB) -URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729 + Details
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