Consolidated Balance Sheet (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 1,251	$ 160
Receivables, net of allowance	3,086	3,086
Inventories	889	908
Drilling advances	452	584
Derivative instruments	3	31
Prepaid assets and other	335	193
Total current assets	6,016	4,962
Oil and gas, on the basis of full-cost accounting:
Proved properties	81,111	78,383
Unproved properties and properties under development, not being amortized	8,328	8,754
Gathering, transmission and processing facilities	6,791	5,955
Other	1,071	1,055
Property and equipment, gross	97,301	94,147
Less: Accumulated depreciation, depletion and amortization	(45,839)	(40,867)
Property and equipment, net	51,462	53,280
OTHER ASSETS:
Goodwill	1,369	1,289
Deferred charges and other	1,392	1,206
Total assets	60,239	60,737
CURRENT LIABILITIES:
Accounts payable	1,345	1,092
Current debt	57	990
Current asset retirement obligation	139	478
Derivative instruments	205	116
Other current liabilities	2,777	2,860
Total current liabilities	4,523	5,536
LONG-TERM DEBT	10,868	11,355
DEFERRED CREDITS AND OTHER NONCURRENT LIABILITIES:
Income taxes	8,297	8,024
Asset retirement obligation	3,123	4,100
Other	447	391
Total deferred credits and other noncurrent liabilities	11,867	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 converted in 2013, 1,265,000 shares issued and outstanding in 2012		1,227
Common stock, $0.625 par, 860,000,000 shares authorized, 407,897,495 and 392,712,245 shares issued, respectively	255	245
Paid-in capital	11,191	9,859
Retained earnings	21,938	20,161
Treasury stock, at cost, 3,977,524 and 1,071,475 shares, respectively	(280)	(30)
Accumulated other comprehensive loss	(123)	(131)
Total shareholders' equity	32,981	31,331
Total liabilities and shareholders' equity	$ 60,239	$ 60,737