Fair Value (Details Textuals) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Option, Quantitative Disclosures [Line Items]
Transfers Between Levels 1, 2 and 3	$ 0	$ 0
Unrealized Losses on Available for Sale Securities	0	0
Trading Securities, Change in Unrealized Holding Gain (Loss)	19,000,000	9,000,000	3,000,000
Equity Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Nuclear Decommissioning Trust Fund Investments	61.00%	61.00%
Debt Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Nuclear Decommissioning Trust Fund Investments	37.00%	38.00%
Cash and Cash Equivalents [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Nuclear Decommissioning Trust Fund Investments	2.00%	1.00%
Fair Value, Measurements, Recurring [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	116,000,000	116,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	114,000,000	116,000,000
Restricted Assets [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	100,000,000	102,000,000
Other Investments [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	16,000,000
Other Investments [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Available-for-sale Securities, Fair Value Disclosure	7,000,000	5,000,000
Other Investments [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents		14,000,000
Nuclear Decommissioning Trust Fund [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Average Maturity of Debt Securities	7 years	6 years
Nuclear Decommissioning Trust Fund [Member] | Cash and Cash Equivalents [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Cash and cash equivalents	19,000,000	7,000,000
Fermi 2 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses recognized as regulatory assets	31,000,000	44,000,000
Fermi 1 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 0	$ 0	$ 0