Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income	$ 181,421	$ 609,504
Adjustments to reconcile net income to net cash provided by operating activities:
Depletion, depreciation and amortization	382,339	258,345
Impairment of oil and gas properties	444,880	0
Exploration expenses, including dry holes	39,730	4,275
Deferred income taxes	(57,291)	(87,337)
Gain (loss) on disposition of assets, net	(44,736)	2,487
Accretion of discount on asset retirement obligations	4,874	4,092
Discontinued operations	3,597	(390,868)
Interest expense	18,152	15,432
Derivative related activity	(144,000)	56,380
Amortization of stock-based compensation	30,970	21,155
Amortization of deferred revenue	(20,919)	(22,290)
Other noncash items	(7,513)	(9,207)
Change in operating assets and liabilities, net of effects from acquisitions and dispositions:
Accounts receivable, net	33,881	(23,605)
Income taxes receivable	(1,452)	27,226
Inventories	(33,318)	(74,136)
Prepaid expenses	(13,425)	(9,990)
Other current assets	(8,846)	8,772
Accounts payable	30,580	6,201
Interest payable	82	(1,642)
Income taxes payable	(7,907)	(11,485)
Other current liabilities	20,271	(6,471)
Net cash provided by operating activities	925,410	564,454
Cash flows from investing activities:
Proceeds from disposition of assets, net of cash sold	62,945	813,520
Payments for acquisition, net of cash acquired	(295,974)	0
Investment in unconsolidated subsidiary	0	(82,857)
Additions to oil and gas properties	(1,424,807)	(757,148)
Additions to other assets and other property and equipment, net	(164,230)	(215,367)
Net cash used in investing activities	(1,822,066)	(241,852)
Cash flows from financing activities:
Borrowings under long-term debt	1,339,093	72,610
Principal payments on long-term debt	(596,000)	(115,810)
Distributions to noncontrolling interests	(17,956)	(13,366)
Payments of other liabilities	(744)	(305)
Exercise of long-term incentive plan stock options	1,008	362
Purchases of treasury stock	(56,317)	(39,218)
Excess tax benefits from share-based payment arrangements	17,545	27,937
Payment of financing fees	(4,660)	(8,739)
Dividends paid	(5,028)	(4,812)
Net cash provided by (used in) financing activities	676,941	(81,341)
Net increase (decrease) in cash and cash equivalents	(219,715)	241,261
Cash and cash equivalents, beginning of period	537,484	111,160
Cash and cash equivalents, end of period	$ 317,769	$ 352,421