Fair Value of Financial Instruments (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2012 Equity securities	Jun. 30, 2012 Equity securities	Dec. 31, 2011 Recurring Level 1	Dec. 31, 2011 Recurring Level 1 Equity securities	Jun. 30, 2012 Recurring Level 2	Dec. 31, 2011 Recurring Level 2	Jun. 30, 2012 Recurring Level 2 Interest rate cap	Dec. 31, 2011 Recurring Level 2 Interest rate cap	Dec. 31, 2011 Recurring Level 2 Natural Gas Hedge	Jun. 30, 2012 Recurring Level 2 Interest rate swaps	Dec. 31, 2011 Recurring Level 2 Interest rate swaps	Jun. 30, 2012 Recurring Total Fair Value	Dec. 31, 2011 Recurring Total Fair Value	Jun. 30, 2012 Recurring Total Fair Value Interest rate cap	Dec. 31, 2011 Recurring Total Fair Value Interest rate cap	Dec. 31, 2011 Recurring Total Fair Value Natural Gas Hedge	Jun. 30, 2012 Recurring Total Fair Value Interest rate swaps	Dec. 31, 2011 Recurring Total Fair Value Interest rate swaps	Dec. 31, 2011 Recurring Total Fair Value Equity securities
Fair value information
Trading securities				$ 12,369,000															$ 12,369,000
Available-for-sale securities				12,099,000															12,099,000
Total assets							81,000	432,000	4,050,000					81,000	432,000	4,050,000
Total assets			24,468,000		81,000	4,482,000						81,000	28,950,000
Derivative liabilities										6,594,000	5,683,000						6,594,000	5,683,000
Recorded loss related to trading securities still held	(5,900,000)	(12,400,000)
Realized losses on sale of available-for-sale securities		$ (452,000)