Income taxes (Narrative) (Details) $ in Millions	12 Months Ended
Nov. 30, 2016 USD ($)
Change in control percentage	50.00%
Losses In Canada Subject To Limitations [Member]
Loss carryforwards	$ 15.2
Approximationss [Member]
Loss carryforwards	153.1
Approximationss [Member] \| US Losses Subject To Limitations [Member]
U.S. carryforward losses	$ 39.4

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign operating loss carryforwards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32621-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32632-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 20
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=68052875&loc=d3e28680-109314

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant