ADDITIONAL BALANCE SHEET INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Accounts receivable, net
Trade accounts	$ 190,328	$ 215,361
Joint interest billing	1,493	7,261
Income taxes receivable	0	922
Other accounts	439	746
Accounts receivable, gross	192,260	224,290
Allowance for doubtful accounts	(990)	(1,814)
Accounts receivable, net	191,270	222,476
Inventories
Natural gas in storage	3,596	9,056
Tubular goods and well equipment	10,080	8,396
Other accounts	55	16
Inventory, net	13,731	17,468
Other current assets
Prepaid balances and other	2,730	2,587
Derivative instruments	16,503	3,019
Other current assets	19,233	5,606
Other assets
Deferred compensation plan	12,815	12,507
Debt issuance cost	18,725	16,476
Other accounts	70	79
Other assets	31,610	29,062
Accounts payable
Trade accounts	53,938	26,023
Natural gas purchases	6,813	2,052
Royalty and other owners	102,933	79,150
Accrued capital costs	185,525	146,899
Taxes other than income	12,906	13,677
Drilling advances	89	14,093
Other accounts	17,583	6,907
Accounts payable current	379,787	288,801
Accrued liabilities
Employee benefits	18,798	43,599
Taxes other than income	10,459	6,894
Interest payable	12,833	20,211
Derivative instruments	102	13,912
Other accounts	2,651	2,897
Accrued liabilities	44,843	87,513
Other liabilities
Deferred compensation plan	30,277	33,211
Derivative instruments	549	0
Other accounts	6,963	13,043
Other liabilities	$ 37,789	$ 46,254