Supplemental Disclosures to the Statements of Cash Flows (Details) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Supplemental Disclosures to the Statements of Cash Flows
Cash payments for interest, net of $7,159,000 and $7,402,000 capitalized in 2012 and 2011, respectively	$ 28,289,000	$ 23,583,000
Interest cost capitalized	7,159,000	7,402,000
Cash payments for federal and state income taxes	1,200,000	925,000
In-kind distributions of Series A convertible preferred units	26,751,000	24,235,000
Unpaid change in liabilities for investing activities	14,177,000	18,658,000
Unpaid capital expenditures	$ 40,370,000	$ 26,657,000