Consolidated Balance Sheet (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 248	$ 160
Receivables, net of allowance	3,106	3,086
Inventories	885	908
Drilling advances	365	584
Derivative instruments	16	31
Prepaid assets and other	228	193
Total current assets	4,848	4,962
Oil and gas, on the basis of full-cost accounting:
Proved properties	80,631	78,383
Unproved properties and properties under development, not being amortized	8,574	8,754
Gathering, transmission and processing facilities	6,293	5,955
Other	1,078	1,055
Property and equipment, gross	96,576	94,147
Less: Accumulated depreciation, depletion and amortization	(42,287)	(40,867)
Property and equipment, net	54,289	53,280
OTHER ASSETS:
Goodwill	1,369	1,289
Deferred charges and other	1,286	1,206
Total Assets	61,792	60,737
CURRENT LIABILITIES:
Accounts payable	1,226	1,092
Current debt	994	990
Current asset retirement obligation	468	478
Derivative instruments	151	116
Other current liabilities	2,723	2,860
Total current liabilities	5,562	5,536
LONG-TERM DEBT	11,485	11,355
DEFERRED CREDITS AND OTHER NONCURRENT LIABILITIES:
Income taxes	8,163	8,024
Asset retirement obligation	4,197	4,100
Other	398	391
Total deferred credits and other noncurrent liabilities	12,758	12,515
COMMITMENTS AND CONTINGENCIES (Note 8)
SHAREHOLDERS' EQUITY:
Preferred stock, no par value, 10,000,000 shares authorized, 6% Cumulative Mandatory Convertible, Series D, $1,000 per share liquidation preference, 1,265,000 shares issued and outstanding	1,227	1,227
Common stock, $0.625 par, 860,000,000 shares authorized, 392,914,549 and 392,712,245 shares issued, respectively	245	245
Paid-in capital	9,897	9,859
Retained earnings	20,781	20,161
Treasury stock, at cost, 1,070,654 and 1,071,475 shares, respectively	(30)	(30)
Accumulated other comprehensive loss	(133)	(131)
Total shareholders' equity	31,987	31,331
Total liabilities and shareholders' equity	$ 61,792	$ 60,737