Impairments (Details) - USD ($)		3 Months Ended					9 Months Ended
	May 13, 2016	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Jul. 14, 2017	May 12, 2016
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses		$ 14,000,000		$ 9,000,000			$ 77,000,000	$ 65,000,000
Construction in progress			$ 0
Other impairments				8,000,000
Impairment loss on investment								$ 147,000,000
Petra Nova Parish Holdings
Impaired Long-Lived Assets Held and Used [Line Items]
Ownership percentage						50.00%
Impairment loss on investment						$ 140,000,000
Other Intangible Assets
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					$ 8,000,000
Deferred Marketing Expenses
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					10,000,000
Investments
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses				$ 9,000,000
Rockford
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					17,000,000
Percentage of ownership										100.00%
Proceeds from sale of property, plant, and equipment	$ 55,000,000
Renewables
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses		$ 14,000,000	22,000,000
Collectibility of receivables | BTEC New Albany, LLC
Impaired Long-Lived Assets Held and Used [Line Items]
Amount owed from BTEC New Albany, LLC									$ 48,000,000
Collectibility of receivables | Purchaser incurred costs | BTEC New Albany, LLC
Impaired Long-Lived Assets Held and Used [Line Items]
Amount owed from BTEC New Albany, LLC									38,000,000
Collectibility of receivables | Liquidation damages | BTEC New Albany, LLC
Impaired Long-Lived Assets Held and Used [Line Items]
Amount owed from BTEC New Albany, LLC									$ 10,000,000
Construction in Progress
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses			$ 41,000,000
Solar Panels
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment losses					$ 17,000,000