CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING REVENUES
Total revenues from contracts with customers	$ 1,985,469	$ 2,143,716	$ 1,747,293
Gain on derivative instruments	80,808	44,432	16,926
Total operating revenues	2,066,277	2,188,148	1,764,219
OPERATING EXPENSES
Direct operations	76,958	69,646	102,310
Taxes other than income	17,053	22,642	33,487
Exploration	20,270	113,820	21,526
Depreciation, depletion and amortization	405,733	417,479	568,817
Impairment of oil and gas properties	0	0	482,811
General and administrative	94,870	96,641	97,786
TOTAL OPERATING EXPENSES	1,189,561	1,401,157	1,803,428
Earnings (loss) on equity method investments	80,496	1,137	(100,486)
Loss on sale of assets	(1,462)	(16,327)	(11,565)
INCOME (LOSS) FROM OPERATIONS	955,750	771,801	(151,260)
Interest expense, net	54,952	73,201	82,130
Other expense (income)	574	463	(4,955)
Income (loss) before income taxes	900,224	698,137	(228,435)
Income tax expense (benefit)	219,154	141,094	(328,828)
NET INCOME	$ 681,070	$ 557,043	$ 100,393
Earnings per share
Basic (in dollars per share)	$ 1.64	$ 1.25	$ 0.22
Diluted (in dollars per share)	$ 1.63	$ 1.24	$ 0.22
Weighted-average common shares outstanding
Basic (in shares)	415,514	445,538	463,735
Diluted (in shares)	417,451	447,568	465,551
Natural gas
OPERATING REVENUES
Total revenues from contracts with customers	$ 1,985,240	$ 1,881,150	$ 1,506,078
Crude oil and condensate
OPERATING REVENUES
Total revenues from contracts with customers	0	48,722	212,338
Brokered natural gas
OPERATING REVENUES
Total revenues from contracts with customers	0	209,530	17,217
OPERATING EXPENSES
Operating expenses	0	184,198	15,252
Other
OPERATING REVENUES
Total revenues from contracts with customers	229	4,314	11,660
Transportation and gathering
OPERATING EXPENSES
Operating expenses	$ 574,677	$ 496,731	$ 481,439