Fair Value of Financial Instruments (Details-3)	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Fair Value Inputs Assets Quantitative Information [Line Items]
Basis adjustment - on peak	97.50%	98.10%
Basis adjustment - off peak	94.70%	95.00%
US Treasury Bill Securities [Member]
Deferred compensation plan [Abstract]
Investment interest calculation, investment maturity period (26 weeks)	182 days
Investment interest calculation, monthly compounding rate	1.00%
Investment interest calculation, minimum annual rate compounded monthly	7.00%
Minimum [Member]
Counterparty fuel mix [Abstract]
Internal generation	60.00%	50.00%
Purchased power	40.00%	50.00%
Maximum [Member]
Counterparty fuel mix [Abstract]
Internal generation	75.00%	70.00%
Purchased power	25.00%	30.00%

Investment maturity period used in deferred compensation interest calculation.

No definition available.

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- Definition

Minimum annual rate compounded monthly used in deferred compensation interest calculation.

+ References

No definition available.

+ Details

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- Definition

Percentage increase compounded monthly used in deferred compensation interest calculation.

+ References

No definition available.

+ Details

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- Details

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- Definition

Estimate of counterparty's internal generation as a portion of their fuel mix, used as an input to measure fair value.

+ References

No definition available.

+ Details

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- Definition

Estimate of counterparty's purchased power as a portion of their fuel mix, used as an input to measure fair value.

+ References

No definition available.

+ Details

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- Definition

Basis adjustment between delivery points for off peak electric future prices. Used as an input to measure fair value.

+ References

No definition available.

+ Details

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- Definition

Basis adjustment between delivery points for on peak electric future prices. Used as an input to measure fair value.

+ References

No definition available.

+ Details

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- Details

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