Supplemental Information on Oil and Gas Producing Activities (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Supplemental Information on Oil and Gas Producing Activities (Unaudited)

Schedule of capitalized costs relating to oil and gas producing activities

	Year ended December 31,
(In thousands)	2017		2018
Proved properties	$	11,096,462		12,705,672
Unproved properties		2,266,673		1,767,600
		13,363,135		14,473,272
Accumulated depletion and depreciation		(2,783,832)		(3,615,680)
Net capitalized costs	$	10,579,303		10,857,592

Schedule of costs incurred in certain oil and gas activities

	Year ended December 31,
(In thousands)	2016		2017		2018
Acquisition costs:
Proved property	$	134,113		175,650		—
Unproved property		611,631		204,272		172,387
Development costs		1,000,903		897,287		1,164,800
Exploration costs		326,856		384,698		323,773
Total costs incurred	$	2,073,503		1,661,907		1,660,960

Schedule of results of operations (including discontinued operations) for oil and gas producing activities

	Year ended December 31,
(In thousands)	2016		2017		2018
Revenues	$	1,755,061		2,747,920		3,652,894
Operating expenses:
Production expenses		999,516		1,279,217		1,601,985
Exploration expenses		6,862		8,538		4,958
Depletion and depreciation		700,274		694,332		832,326
Impairment of unproved properties		162,935		159,598		549,437
Results of operations before income tax (expense) benefit		(114,526)		606,235		664,188
Income tax (expense) benefit		43,334		(228,096)		(156,350)
Results of operations	$	(71,192)		378,139		507,838

Schedule of proved developed and undeveloped reserves

	Natural gas (Bcf)	NGLs (MMBbl)	Oil and condensate (MMBbl)	Equivalents (Bcfe)
Proved reserves:
December 31, 2015	9,533	587	26	13,215
Revisions	(2,069)	275	3	(404)
Extensions, discoveries and other additions	1,990	99	9	2,637
Production	(505)	(27)	(2)	(676)
Purchases of reserves	475	23	2	624
Sales of reserves in place	(10)	—	—	(10)
December 31, 2016	9,414	957	38	15,386
Revisions	342	(22)	(6)	176
Extensions, discoveries and other additions	1,644	77	7	2,148
Production	(591)	(36)	(2)	(822)
Purchases of reserves	289	13	1	373
December 31, 2017	11,098	989	38	17,261
Revisions	(1,087)	8	(1)	(1,042)
Extensions, discoveries and other additions	2,125	98	12	2,781
Production	(711)	(43)	(3)	(989)
Purchases of reserves	—	—	—	—
December 31, 2018	11,425	1,052	46	18,011

	Natural gas (Bcf)	NGLs (MMBbl)	Oil and condensate (MMBbl)	Equivalents (Bcfe)
Proved developed reserves:
December 31, 2016	4,426	401	13	6,914
December 31, 2017	5,587	467	16	8,488
December 31, 2018	6,669	600	20	10,389
Proved undeveloped reserves:
December 31, 2016	4,988	556	25	8,472
December 31, 2017	5,511	522	22	8,773
December 31, 2018	4,756	452	26	7,622

Schedule of standardized measure of discounted future net cash flows attributable to proved reserves

	Year ended December 31,
(in millions)	2016		2017		2018
Future cash inflows	$	36,800		55,824		64,199
Future production costs		(21,275)		(26,375)		(30,007)
Future development costs		(3,902)		(3,312)		(3,453)
Future net cash flows before income tax		11,623		26,137		30,739
Future income tax expense		(1,042)		(4,104)		(5,505)
Future net cash flows		10,581		22,033		25,234
10% annual discount for estimated timing of cash flows		(7,294)		(13,406)		(14,756)
Standardized measure of discounted future net cash flows	$	3,287		8,627		10,478

Schedule of weighted average prices used to estimate the Company's total equivalent reserves

December 31, 2016	$	2.39
December 31, 2017	$	3.23
December 31, 2018	$	3.56

Schedule of changes in standardized measure of discounted future net cash flow

	Year ended December 31,
(in millions)	2016		2017		2018
Sales of oil and gas, net of productions costs	$	(756)		(1,469)		(2,051)
Net changes in prices and production costs		(1,540)		3,918		707
Development costs incurred during the period		733		627		755
Net changes in future development costs		212		229		37
Extensions, discoveries and other additions		673		1,448		1,925
Acquisitions		66		258		—
Divestitures		(7)		—		—
Revisions of previous quantity estimates		461		734		(53)
Accretion of discount		363		368		1,018
Net change in income taxes		12		(1,159)		(563)
Other changes		(163)		386		76
Net increase		54		5,340		1,851
Beginning of year		3,233		3,287		8,627
End of year	$	3,287		8,627		10,478