Acquisitions, Dispositions, and Impairment of Long-Lived Assets Acquisitions, Dispositions, and Impairments of Long-Lived Assets (Significant Unobservable Inputs) (Details)	Dec. 31, 2016	Dec. 31, 2015
Indian Point Energy Center Units [Member]
Weighted Average Cost Of Capital Used In Asset Valuation	7.20%
Operating Margin Used In Asset Valuation	19.70%
Palisades [Member]
Weighted Average Cost Of Capital Used In Asset Valuation	6.50%	7.50%
Operating Margin Used In Asset Valuation	34.60%	30.80%
FitzPatrick [Member]
Weighted Average Cost Of Capital Used In Asset Valuation		7.50%
Operating Margin Used In Asset Valuation		10.20%
Pilgrim [Member]
Weighted Average Cost Of Capital Used In Asset Valuation		7.90%
Operating Margin Used In Asset Valuation		8.10%
Minimum [Member] | Indian Point Energy Center Units [Member]
Weighted Average Cost Of Capital Used In Asset Valuation	7.00%
Minimum [Member] | Palisades [Member]
Operating Margin Used In Asset Valuation	17.80%
Minimum [Member] | Pilgrim [Member]
Weighted Average Cost Of Capital Used In Asset Valuation		7.50%
Operating Margin Used In Asset Valuation		2.40%
Maximum [Member] | Indian Point Energy Center Units [Member]
Weighted Average Cost Of Capital Used In Asset Valuation	7.50%
Maximum [Member] | Palisades [Member]
Operating Margin Used In Asset Valuation	38.80%
Maximum [Member] | Pilgrim [Member]
Weighted Average Cost Of Capital Used In Asset Valuation		8.00%
Operating Margin Used In Asset Valuation		10.60%