Concentration of Customers - Schedule of Trade Accounts Receivable from Certain Customers (Detail) - Accounts Receivable [Member] - Customer Concentration Risk [Member]	6 Months Ended	12 Months Ended
Jun. 30, 2017	Dec. 31, 2016
GE [Member]
Concentration Risk [Line Items]
Percentage of Total	23.40%	24.90%
Vestas [Member]
Concentration Risk [Line Items]
Percentage of Total	40.80%	26.20%
Nordex Group [Member]
Concentration Risk [Line Items]
Percentage of Total	29.40%	26.80%
Gamesa [Member]
Concentration Risk [Line Items]
Percentage of Total	4.30%	16.20%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration