CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share data) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Operating revenues and other income:
Oil, gas, and NGL production revenue	$ 1,585,750	[1]	$ 1,636,357	[2]	$ 1,253,783	[3]
Net gain (loss) on divestiture activity	862		426,917		(131,028)
Other operating revenues	3,493		3,798		6,621
Total operating revenues and other income	1,590,105		2,067,072		1,129,376
Operating expenses:
Oil, gas, and NGL production expense	500,709		487,367		507,906
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	823,798		665,313		557,036
Exploration	51,500		55,166		54,713
Impairment of oil and gas properties	33,842		49,889		16,078
General and administrative	132,797		116,504		117,283
Net derivative (gain) loss	97,539		(161,832)		26,414
Other operating expenses, net	19,888		18,328		13,667
Total operating expenses	1,660,073		1,230,735		1,293,097
Income (loss) from operations	(69,968)		836,337		(163,721)
Interest expense	(159,102)		(160,906)		(179,257)
Loss on extinguishment of debt	0		(26,740)		(35)
Other non-operating income (expense), net	(1,974)		3,086		(800)
Income (loss) before income taxes	(231,044)		651,777		(343,813)
Income tax (expense) benefit	44,043		(143,370)		182,970
Net income (loss)	$ (187,001)		$ 508,407		$ (160,843)
Basic weighted-average common shares outstanding	112,544		111,912		111,428
Diluted weighted-average common shares outstanding	112,544		113,502		111,428
Basic net income (loss) per common share	$ (1.66)		$ 4.54		$ (1.44)
Diluted net income (loss) per common share	$ (1.66)		$ 4.48		$ (1.44)

[1] Note: Amounts may not calculate due to rounding.

[2] Note: Amounts may not calculate due to rounding.

[3] Note: Amounts may not calculate due to rounding.