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Basis of Presentation and Recent Developments (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Sales Revenue, Net [Member]
Product Information [Line Items]
Non-regulated segment, percentage	12.00%	11.00%
Net Income [Member]
Product Information [Line Items]
Non-regulated segment, percentage	6.00%	2.00%

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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