Discontinued Operations (Details) - Maine Hydro [Member] $ in Millions	12 Months Ended
	Dec. 31, 2013 USD ($) MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Capacity associated with discontinued operations (in megawatts) | MW	351
Assumption of debt	$ 700
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	372
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	$ 231