Fair Value of Financial Instruments (Details) (USD $)	3 Months Ended
	Mar. 31, 2012 Equity securities	Mar. 31, 2012 Recurring Level 1	Dec. 31, 2011 Recurring Level 1	Mar. 31, 2012 Recurring Level 1 Equity securities	Dec. 31, 2011 Recurring Level 1 Equity securities	Mar. 31, 2012 Recurring Level 2	Dec. 31, 2011 Recurring Level 2	Mar. 31, 2012 Recurring Level 2 Interest rate cap	Dec. 31, 2011 Recurring Level 2 Interest rate cap	Mar. 31, 2012 Recurring Level 2 Natural Gas Hedge	Dec. 31, 2011 Recurring Level 2 Natural Gas Hedge	Mar. 31, 2012 Recurring Level 2 Interest rate swaps	Dec. 31, 2011 Recurring Level 2 Interest rate swaps	Mar. 31, 2012 Recurring Total Fair Value	Dec. 31, 2011 Recurring Total Fair Value	Mar. 31, 2012 Recurring Total Fair Value Interest rate cap	Dec. 31, 2011 Recurring Total Fair Value Interest rate cap	Mar. 31, 2012 Recurring Total Fair Value Natural Gas Hedge	Dec. 31, 2011 Recurring Total Fair Value Natural Gas Hedge	Mar. 31, 2012 Recurring Total Fair Value Interest rate swaps	Dec. 31, 2011 Recurring Total Fair Value Interest rate swaps	Mar. 31, 2012 Recurring Total Fair Value Equity securities	Dec. 31, 2011 Recurring Total Fair Value Equity securities
Fair value information
Trading securities				$ 5,714,000	$ 12,369,000																	$ 5,714,000	$ 12,369,000
Available-for-sale securities					12,099,000																		12,099,000
Total assets								223,000	432,000	2,965,000	4,050,000					223,000	432,000	2,965,000	4,050,000
Total assets		5,714,000	24,468,000			3,188,000	4,482,000							8,902,000	28,950,000
Derivative liabilities												6,479,000	5,683,000							6,479,000	5,683,000
Recorded loss related to trading securities still held	(6,500,000)
Realized loss on sale of available-for-sale securities	$ (452,000)