Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income	$ 220,958	$ 343,804
Adjustments to reconcile net income to net cash provided by operating activities:
Depletion, depreciation and amortization	181,418	126,681
Exploration expenses, including dry holes	27,163	1,481
Deferred income taxes	105,871	(50,305)
(Gain) loss on disposition of assets, net	(43,596)	2,191
Accretion of discount on asset retirement obligations	2,430	2,044
Discontinued operations	1,577	(399,689)
Interest expense	9,870	7,637
Derivative related activity	(27,243)	276,683
Amortization of stock-based compensation	15,086	10,174
Amortization of deferred revenue	(10,459)	(11,083)
Other noncash items	(9,516)	(20,124)
Change in operating assets and liabilities, net of effects from dispositions:
Accounts receivable, net	(20,663)	(25,270)
Income taxes receivable	1,407	1
Inventories	(31,027)	(29,319)
Prepaid expenses	1,413	1,342
Other current assets	2,488	3,305
Accounts payable	19,326	(89,980)
Interest payable	(21,917)	(25,066)
Income taxes payable	16,941	15,354
Other current liabilities	(15,441)	3,353
Net cash provided by operating activities	426,086	143,214
Cash flows from investing activities:
Proceeds from disposition of assets, net of cash sold	58,514	810,470
Investment in unconsolidated subsidiary		(37,048)
Additions to oil and gas properties	(678,339)	(309,974)
Additions to other assets and other property and equipment, net	(59,841)	(129,280)
Net cash provided by (used in) investing activities	(679,666)	334,168
Cash flows from financing activities:
Borrowings under long-term debt	134,000	60,610
Principal payments on long-term debt	(49,000)	(105,810)
Distributions to noncontrolling interests	(8,957)	(6,664)
Borrowings (payments) of other liabilities	458	(20)
Exercise of long-term incentive plan stock options	1,008	337
Purchases of treasury stock	(56,129)	(35,682)
Excess tax benefits from share-based payment arrangements	12,938	28,083
Payment of financing fees	(1,261)	(8,672)
Dividends paid	(43)	(73)
Net cash provided by (used in) financing activities	33,014	(67,891)
Net increase (decrease) in cash and cash equivalents	(220,566)	409,491
Cash and cash equivalents, beginning of period	537,484	111,160
Cash and cash equivalents, end of period	$ 316,918	$ 520,651