Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

Amount of income (expense) related to nonoperating activities, classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864

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-Name Accounting Standards Codification
-Topic 850
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-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Related Party Transactions - Transactions with Joint Ventures (Details) - USD ($) $ in Thousands				3 Months Ended								12 Months Ended
	May 31, 2017	Apr. 13, 2016	Dec. 07, 2012	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Related Party Transaction [Line Items]
Other (income) expense, net				$ 81	$ (68)	$ (95)	$ (94)	$ (226)	$ (10)	$ 2,142	$ 455	$ (176)	$ 2,361
Green Power \| MAT-PSI Holdings, LLC \| Corporate Joint Venture
Related Party Transaction [Line Items]
Ownership percentage			100.00%
Investment amount with related party			$ 900
Percent of noncontrolling interest			50.00%
Doosan-PSI, LLC \| Corporate Joint Venture
Related Party Transaction [Line Items]
Investment amount with related party														$ 1,000
Percent of noncontrolling interest														50.00%
Sterling And Wilson Cogen Solutions, LLC \| SW \| Corporate Joint Venture
Related Party Transaction [Line Items]
Investment amount with related party	$ 200	$ 200
Percent of noncontrolling interest	49.00%	49.00%