Additional Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts receivable, net
Trade accounts	$ 114,154	$ 227,835
Joint interest accounts	1,585	2,245
Other accounts	5,001	6,515
Receivables Gross Current	120,740	236,595
Allowance for doubtful accounts	(997)	(1,198)
Accounts receivable, net	119,743	235,397
Inventories
Tubular goods and well equipment	15,016	10,675
Natural gas in storage	3,205	3,281
Other accounts	62	70
Inventories	18,283	14,026
Other assets
Deferred compensation plan	12,586	13,115
Debt issuance costs	21,791	17,349
Other accounts	62	65
Other assets	34,439	30,529
Accounts payable
Trade accounts	33,312	54,949
Natural gas purchases	1,859	2,407
Royalty and other owners	75,976	97,298
Accrued capital costs	63,324	222,426
Taxes other than income	12,432	16,806
Drilling advances	81	88
Other accounts	4,357	6,102
Accounts payable current	191,341	400,076
Accrued liabilities
Employee benefits	12,501	22,815
Taxes other than income	10,694	7,128
Interest payable	13,595	30,677
Other accounts	2,333	3,049
Accrued liabilities	39,123	63,669
Other liabilities
Deferred compensation plan	24,263	28,932
Other accounts	4,478	10,675
Other liabilities	$ 28,741	$ 39,607