Fair Value of Financial Instruments (Details) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Assets:
Investments, at fair value	$ 4,692,000	$ 3,918,000
Fair Value, Measurements, Recurring [Member] | Mark-to-market energy liabilities [Member]
Liabilities:
Liabilities, Fair Value Disclosure	504,000	1,496,000
Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Assets:
Investments, at fair value	2,098,000	1,734,000
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Assets:
Investments, at fair value	2,594,000	2,224,000
Fair Value, Measurements, Recurring [Member] | Mark-to-market energy assets, including put option [Member]
Assets:
Derivative Assets at fair value		1,754,000
Fair Value, Measurements, Recurring [Member] | Mark-to-market energy assets, including call option [Member]
Assets:
Derivative Assets at fair value	585,000
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets, Level 1 [Member] | Other Investments [Member]
Assets:
Investments, at fair value	2,098,000	1,734,000
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets, Level 1 [Member] | Equity Securities [Member]
Assets:
Investments, at fair value	2,594,000	2,224,000
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs, Level 2 [Member] | Mark-to-market energy liabilities [Member]
Liabilities:
Liabilities, Fair Value Disclosure	504,000	1,496,000
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs, Level 2 [Member] | Mark-to-market energy assets, including put option [Member]
Assets:
Derivative Assets at fair value		1,754,000
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs, Level 2 [Member] | Mark-to-market energy assets, including call option [Member]
Assets:
Derivative Assets at fair value	585,000
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs, Level 3 [Member] | Mark-to-market energy liabilities [Member]
Liabilities:
Liabilities, Fair Value Disclosure
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs, Level 3 [Member] | Other Investments [Member]
Assets:
Investments, at fair value
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs, Level 3 [Member] | Equity Securities [Member]
Assets:
Investments, at fair value
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs, Level 3 [Member] | Mark-to-market energy assets, including put option [Member]
Assets:
Derivative Assets at fair value
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs, Level 3 [Member] | Mark-to-market energy assets, including call option [Member]
Assets:
Derivative Assets at fair value