Significant Accounting Policies (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Significant Accounting Policies [Line Items]
Other Nonoperating Income	$ 55	$ 58	$ 136	$ 148
Effective Income Tax Rate, Continuing Operations	12.00%	28.00%	27.00%	29.00%
Other Information Pertaining to Income Taxes			The 16% decrease in the effective tax rate for the three months ended September 30, 2014 is due to higher production tax credits. The 2% decrease in effective tax rate for the nine months ended September 30, 2014 is due to higher production tax credits, partially offset by $8 million of deferred tax expense resulting from New York state income tax reform enacted on March 31, 2014.
Unrecognized Tax Benefits that would impact Effective Tax Rate	2		2
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecognized Benefit	1		1
Minimum [Member]
Significant Accounting Policies [Line Items]
Finite Lived Asset Useful Life			1 year
Maximum [Member]
Significant Accounting Policies [Line Items]
Finite Lived Asset Useful Life			28 years
Power and Industrial Projects [Member]
Significant Accounting Policies [Line Items]
Other Nonoperating Income	$ 25	$ 25	$ 57	$ 60