Nuclear Decommissioning Trust Fund Investments (Fair Value And The Gross Unrealized Losses Of The Available-For-Sale Securities Held In Nuclear Decommissioning Trust Fund) (Details) (USD $)	Dec. 31, 2014
Nuclear Decommissioning Trust Fund Investments [Line Items]
Less than 12 months, fair value	$ 34,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,000,000
12 months or greater, fair value	13,000,000
Total, fair value	47,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	4,000,000
Debt Securities
Nuclear Decommissioning Trust Fund Investments [Line Items]
Less than 12 months, fair value	28,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1
12 months or greater, fair value	8,000,000
Total, fair value	36,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	1,000,000
Equity Securities
Nuclear Decommissioning Trust Fund Investments [Line Items]
Less than 12 months, fair value	6,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,000,000
12 months or greater, fair value	5,000,000
Total, fair value	11,000,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 4,000,000