CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities:
Net income	$ 49,238,000	$ 170,111,000
Adjustments to reconcile net income to net cash provided from operating activities:
Deferred income tax expense	42,676,000	112,395,000
Depletion, depreciation and amortization and impairment	169,578,000	149,821,000
Exploration dry hole costs	2,000	0
Abandonment and impairment of unproved properties	11,773,000	4,420,000
Derivative fair value loss (income)	14,009,000	(165,557,000)
Cash settlements on derivative financial instruments	8,925,000	(4,181,000)
Amortization of deferred financing costs and other	1,312,000	1,310,000
Deferred and stock-based compensation	18,527,000	962,000
Gain on the sale of assets	(23,000)	(22,600,000)
Changes in working capital:
Accounts receivable	53,913,000	(4,690,000)
Inventory and other	(5,294,000)	2,868,000
Accounts payable	47,453,000	24,384,000
Accrued liabilities and other	(41,517,000)	(43,381,000)
Net cash provided from operating activities	370,572,000	225,862,000
Investing activities:
Additions to natural gas and oil properties	(308,641,000)	(186,727,000)
Additions to field service assets	(239,000)	(1,565,000)
Acreage purchases	(25,355,000)	(28,725,000)
Proceeds from disposal of assets	40,000	26,053,000
Purchases of marketable securities held by the deferred compensation plan	(13,153,000)	(12,388,000)
Proceeds from the sales of marketable securities held by the deferred compensation plan	11,928,000	10,231,000
Net cash used in investing activities	(335,420,000)	(193,121,000)
Financing activities:
Borrowings on credit facilities	528,000,000	448,000,000
Repayments on credit facilities	(557,000,000)	(484,000,000)
Repayment of senior notes	0	(500,000)
Dividends paid	(4,971,000)	(4,951,000)
Taxes paid for shares withheld	(2,659,000)	(5,879,000)
Change in cash overdrafts	922,000	11,803,000
Proceeds from the sales of common stock held by the deferred compensation plan	635,000	3,017,000
Net cash used in financing activities	(35,073,000)	(32,510,000)
Increase in cash and cash equivalents	79,000	231,000
Cash and cash equivalents at beginning of period	448,000	314,000
Cash and cash equivalents at end of period	$ 527,000	$ 545,000