Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities
Net Income (Loss)		$ (604,572)	$ 2,734,910	$ 3,419,040
Items Not Requiring (Providing) Cash
Depreciation, Depletion and Amortization		3,400,353	3,749,704	3,435,408
Impairments		2,099,780	517,896	347,021
Stock-Based Compensation Expenses		146,396	174,738	155,337
Deferred Income Taxes		(186,390)	631,658	894,156
(Gains) Losses on Asset Dispositions, Net		46,883	(123,613)	(174,562)
Other, Net		12,826	4,496	7,066
Dry Hole Costs	[1]	13,083	28,001	5,405
Mark-to-Market Commodity Derivative Contracts
Total (Gains) Losses		(1,144,737)	(180,275)	165,640
Net Cash Received from (Payments for) Settlements of Commodity Derivative Contracts		1,070,647	231,229	(258,906)
Other, Net		1,354	962	3,108
Changes in Components of Working Capital and Other Assets and Liabilities
Accounts Receivable		466,523	(91,792)	(368,180)
Inventories		122,647	90,284	(395,408)
Accounts Payable		(795,267)	168,539	439,347
Accrued Taxes Payable		(49,096)	40,122	(92,461)
Other Assets		324,521	358,001	(125,435)
Other Liabilities		8,098	(56,619)	10,949
Changes in Components of Working Capital Associated with Investing and Financing Activities		74,734	(115,061)	301,083
Net Cash Provided by Operating Activities		5,007,783	8,163,180	7,768,608
Investing Cash Flows
Additions to Oil and Gas Properties		(3,243,474)	(6,151,885)	(5,839,294)
Additions to Other Property, Plant and Equipment		(221,226)	(270,641)	(237,181)
Proceeds from Sales of Assets		191,928	140,292	227,446
Payments for (Proceeds from) Other Investing Activities		0	(10,000)	(19,993)
Changes in Components of Working Capital Associated with Investing Activities		(74,734)	115,061	(301,140)
Net Cash Used in Investing Activities		(3,347,506)	(6,177,173)	(6,170,162)
Financing Cash Flows
Long-Term Debt Repayments		(1,000,000)	(900,000)	(350,000)
Dividends Paid		(820,823)	(588,200)	(438,045)
Treasury Stock Purchased		(16,130)	(25,152)	(63,456)
Proceeds from Stock Options Exercised and Employee Stock Purchase Plan		16,169	17,946	20,560
Debt Issuance Costs		(2,649)	(5,016)	0
Repayment of Capital Lease Obligation		(19,444)	(12,899)	(8,219)
Other, Net		0	0	57
Net Cash Used in Financing Activities		(359,025)	(1,513,321)	(839,103)
Effect of Exchange Rate Changes on Cash		(296)	(348)	(37,937)
Increase in Cash and Cash Equivalents		1,300,956	472,338	721,406
Cash and Cash Equivalents at Beginning of Year		2,027,972	1,555,634	834,228
Cash and Cash Equivalents at End of Year		3,328,928	2,027,972	1,555,634
Proceeds from Issuance of Senior Long-term Debt		$ 1,483,852	$ 0	$ 0

[1] Excludes gains or losses on the mark-to-market of financial commodity derivative contracts, gains or losses on sales of reserves and related assets, interest charges and general corporate expenses for each of the three years in the period ended December 31, 2020.