Summary of Significant Accounting Policies - Derivative Financial Instruments (Details) CAD in Millions	Sep. 30, 2017 CAD contract
Accounting Policies [Abstract]
Number of foreign currency denominated contracts outstanding \| contract	1
Discontinued operations, note due from buyer \| CAD	CAD 27.6

The number of derivative instruments of a particular group held by the entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant