Accounts Receivable and Accounts Payable and Accrued Expenses Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	$ 210,368	$ 163,190
Accrued oil, gas, and NGL sales
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	149,384	108,393
Due From Joint Interest Owner
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	30,784	50,018
Taxes Receivable
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	14,979	2,114
Other Receivables
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	15,221	2,665
Total Current Accounts Receivable
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	$ 210,368	$ 163,190