Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
OPERATING ACTIVITIES:
Net income	$ 178,827	$ 133,445
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization	294,412	242,590
Loss on derivatives	9,234	3,542
Cash payments on derivatives settled	(18,984)	(1,777)
Deferred tax expense	87,802	77,566
Gain on disposition of assets	(9,092)	(7,744)
Employee stock compensation plans	17,780	16,652
Other, net	5,156	4,263
Changes in operating assets and liabilities increasing (decreasing) cash:
Accounts receivable	(47,704)	1,888
Accounts payable	1,708	320
Material and supplies	2,222	(1,767)
Accrued liabilities	28,596	31,041
Other, net	(430)	942
Net cash provided by operating activities	549,527	500,961
INVESTING ACTIVITIES:
Capital expenditures	(686,405)	(512,574)
Proceeds from disposition of assets	49,341	89,916
Other	303	0
Net cash used in investing activities	(636,761)	(422,658)
FINANCING ACTIVITIES:
Borrowings under credit agreement	395,700	222,500
Payments under credit agreement	(364,900)	(293,600)
Payments on capitalized leases	(1,505)	0
Proceeds from exercise of stock options	926	578
Book overdrafts	39,315	(7,014)
Net cash provided by (used in) financing activities	69,536	(77,536)
Net increase (decrease) in cash and cash equivalents	(17,698)	767
Cash and cash equivalents, beginning of period	18,593	974
Cash and cash equivalents, end of period	895	1,741
Cash paid during the year for:
Interest paid (net of capitalized)	(1,340)	(1,301)
Income taxes	16,000	7,300
Changes in accounts payable and accrued liabilities related to purchases of property, plant, and equipment	(42,651)	(516)
Non-cash reductions to oil and natural gas properties related to asset retirement obligations	40,516	16,417
Non-cash additions to property, plant, and equipment acquired under capital leases	$ (28,202)	$ 0