ADDITIONAL BALANCE SHEET INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accounts receivable, net
Trade accounts	$ 182,863	$ 227,835
Joint interest accounts	2,016	2,245
Income taxes receivable	2,441	3,612
Other accounts	(614)	6,515
Accounts receivable, gross	186,706	240,207
Allowance for doubtful accounts	(1,425)	(1,198)
Accounts receivable, net	185,281	239,009
Inventories
Natural gas in storage	2,394	3,281
Tubular goods and well equipment	11,535	10,675
Other accounts	158	70
Inventory, net	14,087	14,026
Other assets
Deferred compensation plan	13,322	13,115
Debt issuance cost	16,082	17,349
Other accounts	184	65
Other assets	29,588	30,529
Accounts payable
Trade accounts	68,891	54,949
Natural gas purchases	2,164	2,407
Royalty and other owners	93,316	97,298
Accrued capital costs	130,782	222,426
Taxes other than income	20,464	16,806
Drilling advances	87	88
Other accounts	5,511	6,102
Accounts payable current	321,215	400,076
Accrued liabilities
Employee benefits	10,819	22,815
Taxes other than income	7,455	7,128
Interest payable	13,755	30,677
Other accounts	2,550	3,049
Accrued liabilities	34,579	63,669
Other liabilities
Deferred compensation plan	29,096	28,932
Other accounts	9,312	10,675
Other liabilities	$ 38,408	$ 39,607