Fair value measurements (Details Textual) - Aerex Industries Inc [Member]	Jun. 30, 2018	Feb. 29, 2016
Business Acquisition, Percentage of Voting Interests Acquired	51.00%	51.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		49.00%

Percentage of voting equity interests acquired at the acquisition date in the business combination.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant