Accounts Receivable and Accounts Payable and Accrued Expenses Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	$ 134,124	$ 322,630
Accrued oil, gas, and NGL production revenue [Member]
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	58,256	180,250
Amounts due From Joint Interest Owners [Member]
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	22,269	58,347
Accrued derivative settlements [Member]
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	34,579	39,811
State severance tax refunds [Member]
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	12,072	24,394
Other [Member]
Accounts, Notes, Loans and Financing Receivable
Accounts Receivable, Net, Current	$ 6,948	$ 19,828