CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
OPERATING REVENUES
Operating revenues	$ 457,115	$ 446,652	$ 924,765	$ 931,112
Gain (loss) on derivative instruments	(3,668)	13,805	1,909	47,190
TOTAL OPERATING REVENUES	453,447	460,457	926,674	978,302
OPERATING EXPENSES
Direct operations	15,657	27,262	35,727	51,903
Taxes other than income	5,392	8,310	12,582	17,368
Exploration	54,500	3,959	58,117	10,157
Depreciation, depletion and amortization	84,910	144,322	167,038	279,422
Impairment of oil and gas properties and other assets	0	68,555	0	68,555
General and administrative	21,228	23,957	45,288	47,659
TOTAL OPERATING EXPENSES	375,958	400,328	630,098	726,547
Loss on equity method investments	(4)	(1,286)	(998)	(2,569)
Gain (loss) on sale of assets	544	(1,403)	(40,505)	(1,626)
INCOME FROM OPERATIONS	78,029	57,440	255,073	247,560
Interest expense, net	23,328	20,619	43,386	41,390
Other (income) expense	118	(315)	232	109
Income before income taxes	54,583	37,136	211,455	206,061
Income tax expense	12,152	15,609	51,793	78,814
NET INCOME	$ 42,431	$ 21,527	$ 159,662	$ 127,247
Earnings per share
Basic (in dollars per share)	$ 0.09	$ 0.05	$ 0.35	$ 0.27
Diluted (in dollars per share)	$ 0.09	$ 0.05	$ 0.35	$ 0.27
Weighted-average common shares outstanding
Basic (in shares)	451,055	464,768	455,361	465,057
Diluted (in shares)	453,114	466,745	457,142	466,752
Dividends per common share (in dollars per share)	$ 0.06	$ 0.05	$ 0.12	$ 0.07
Natural gas
OPERATING REVENUES
Operating revenues	$ 364,660	$ 395,328	$ 776,768	$ 828,770
Crude oil and condensate
OPERATING REVENUES
Operating revenues	0	44,625	48,722	87,616
Brokered natural gas
OPERATING REVENUES
Operating revenues	92,576	4,037	97,526	8,732
OPERATING EXPENSES
Operating expenses	80,082	3,419	85,032	7,465
Other
OPERATING REVENUES
Operating revenues	(121)	2,662	1,749	5,994
Transportation and gathering
OPERATING EXPENSES
Operating expenses	$ 114,189	$ 120,544	$ 226,314	$ 244,018