Consolidated Balance Sheets (unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Current Assets
Cash and Cash Equivalents	$ 1,143	$ 1,455
Accounts Receivable, Net	919	783
Other Current Assets	330	180
Total Current Assets	2,392	2,418
Property, Plant and Equipment
Oil and Gas Properties (Successful Efforts Method of Accounting)	18,527	17,703
Property, Plant and Equipment, Other	317	294
Total Property, Plant and Equipment, Gross	18,844	17,997
Accumulated Depreciation, Depletion and Amortization	(5,460)	(5,215)
Total Property, Plant and Equipment, Net	13,384	12,782
Goodwill	696	696
Other Noncurrent Assets	592	548
Total Assets	17,064	16,444
Current Liabilities
Accounts Payable - Trade	1,457	1,343
Other Current Liabilities	951	925
Total Current Liabilities	2,408	2,268
Long-Term Debt	4,088	4,100
Deferred Income Taxes, Noncurrent	2,216	2,059
Other Noncurrent Liabilities	819	752
Total Liabilities	9,531	9,179
Commitments and Contingencies
Shareholders' Equity
Preferred Stock - Par Value $1.00 per share; 4 Million Shares Authorized, None Issued	0	0
Common Stock - Par Value $3.33 1/3 per share; 250 Million Shares Authorized; 198 Million and 197 Million Shares Issued, Respectively	659	656
Additional Paid in Capital	2,549	2,497
Accumulated Other Comprehensive Loss	(98)	(100)
Treasury Stock, at Cost; 19 Million Shares	(651)	(638)
Retained Earnings	5,074	4,850
Total Shareholders' Equity	7,533	7,265
Total Liabilities and Shareholders' Equity	$ 17,064	$ 16,444