Assets and Liabilities with Recurring Fair Value Measurements Quantitative Info on Level 3 (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Physical Power [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information Power		$ 7,000,000
Physical Power [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information Power		28.92
Physical Power [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information Power		53.15
Power Congestion Products [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information Power	7,000,000	7,000,000
Power Congestion Products [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information Power	(8.79)	(8.79)
Power Congestion Products [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information Power	$ 11.53	$ 11.53