OIL AND GAS RESERVE DATA (UNAUDITED) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 MBbls MMBoe	Dec. 31, 2012 MBbls	Dec. 31, 2011 MBbls
Proved reserves
Capital costs of conversion of proved undeveloped reserves to proved developed reserves	$ 32.8
Mbbls
Proved reserves
Beginning of year	16,380	14,963	10,250
Purchase of reserves in place	128
Discoveries and extensions	500	3,337	3,744
Revisions of previous estimates	171	(811)	1,880
Production	(1,105)	(1,109)	(911)
End of year	16,074	16,380	14,963
Proved developed reserves- Beginning of year	8,064	8,348	7,518
Proved developed reserves- End of year	8,512	8,064	8,348
Proved undeveloped reserves- Beginning of year	8,316	6,615	2,732
Proved undeveloped reserves- End of year	7,562	8,316	6,615
Undeveloped reserves transferred to developed reserves	1.1
Year-end upward revision	800
Year-end upward revision due to performance	200
Year-end upward revision due to discoveries and extensions	500
Year-end upward revision due to purchase of additional interest	100
Mmcf
Proved reserves
Beginning of year	51,236	43,860	68,200
Purchase of reserves in place		20,649
Discoveries and extensions	46,532	2,054
Revisions of previous estimates	14,492	(9,813)	(19,320)
Production	(6,232)	(5,514)	(5,020)
End of year	106,028	51,236	43,860
Proved developed reserves- Beginning of year	51,236	28,515	49,300
Proved developed reserves- End of year	78,038	51,236	28,515
Proved undeveloped reserves- Beginning of year		15,345	18,900
Proved undeveloped reserves- End of year	27,990		15,345
Year-end upward revision	61,000
Year-end upward revision due to pricing	9,000
Year-end upward revision due to performance	5,500