Consolidated Balance Sheet (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 184	$ 160
Receivables, net of allowance	2,914	3,086
Inventories	973	908
Drilling advances	298	584
Derivative instruments	87	31
Prepaid assets and other	302	193
Total current assets	4,758	4,962
Oil and gas, on the basis of full-cost accounting:
Proved properties	83,287	78,383
Unproved properties and properties under development, not being amortized	8,628	8,754
Gathering, transmission and processing facilities	6,547	5,955
Other	1,031	1,055
Property and equipment, gross	99,493	94,147
Less: Accumulated depreciation, depletion and amortization	(43,672)	(40,867)
Property and equipment, net	55,821	53,280
OTHER ASSETS:
Goodwill	1,369	1,289
Deferred charges and other	1,402	1,206
Total assets	63,350	60,737
CURRENT LIABILITIES:
Accounts payable	1,346	1,092
Current debt	478	990
Current asset retirement obligation	475	478
Derivative instruments	22	116
Other current liabilities	2,837	2,860
Total current liabilities	5,158	5,536
LONG-TERM DEBT	12,297	11,355
DEFERRED CREDITS AND OTHER NONCURRENT LIABILITIES:
Income taxes	8,496	8,024
Asset retirement obligation	4,278	4,100
Other	400	391
Total deferred credits and other noncurrent liabilities	13,174	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, 393,364,730 and 392,712,245 shares issued, respectively	246	245
Paid-in capital	9,928	9,859
Retained earnings	21,718	20,161
Treasury stock, at cost, 3,983,401 and 1,071,475 shares, respectively	(280)	(30)
Accumulated other comprehensive loss	(118)	(131)
Total shareholders' equity	32,721	31,331
Total liabilities and shareholders' equity	$ 63,350	$ 60,737