CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING REVENUES
Natural gas	$ 412,108	$ 433,442
Crude oil and condensate	48,722	42,990
Gain on derivative instruments	5,577	33,384
Brokered natural gas	4,950	4,695
Other	1,870	3,332
TOTAL OPERATING REVENUES	473,227	517,843
OPERATING EXPENSES
Direct operations	20,070	24,641
Transportation and gathering	112,125	123,474
Brokered natural gas	4,950	4,046
Taxes other than income	7,190	9,058
Exploration	3,617	6,198
Depreciation, depletion and amortization	82,128	135,100
General and administrative	24,060	23,700
TOTAL OPERATING EXPENSES	254,140	326,217
Loss on equity method investments	(994)	(1,283)
Loss on sale of assets	(41,049)	(223)
INCOME FROM OPERATIONS	177,044	190,120
Interest expense, net	20,058	20,771
Other expense	114	424
Income before income taxes	156,872	168,925
Income tax expense	39,641	63,205
NET INCOME	$ 117,231	$ 105,720
Earnings per share
Basic (in dollars per share)	$ 0.26	$ 0.23
Diluted (in dollars per share)	$ 0.25	$ 0.23
Weighted-average common shares outstanding
Basic (in shares)	459,715	465,348
Diluted (in shares)	461,549	466,888
Dividends per common share (in dollars per share)	$ 0.06	$ 0.02