OIL AND GAS RESERVE DATA (UNAUDITED) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended
	Oct. 09, 2012 Mcfe	Dec. 31, 2012 Mcfe MMcf	Dec. 31, 2011 MMcf	Dec. 31, 2010 MMcf
Proved reserves
Capital costs of conversion of proved undeveloped reserves to proved developed reserves		32.4
Mbbls
Proved reserves
Beginning of year		14,963	10,250	10,221
Discoveries and extensions		3,337	3,744	658
Revisions of previous estimates		(811)	1,880	340
Production		(1,109)	(911)	(969)
End of year		16,380	14,963	10,250
Proved developed reserves- Beginning of year		8,348	7,518	7,933
Proved developed reserves- End of year		8,064	8,348	7,518
Proved undeveloped reserves- Beginning of year		6,615	2,732	2,288
Proved undeveloped reserves- End of year		8,316	6,615	2,732
Undeveloped reserves transferred to developed reserves		0.9
Year-end upward revision		2.5
Year-end upward revision due to discoveries and extensions		3.3
Year-end downward revision due to performance		0.8
Mmcf
Proved reserves
Beginning of year		43,860	68,200	62,900
Purchase of reserves in place		20,649		3,037
Discoveries and extensions		2,054
Revisions of previous estimates		(9,813)	(19,320)	6,915
Production		(5,514)	(5,020)	(4,652)
End of year		51,236	43,860	68,200
Proved developed reserves- Beginning of year		28,515	49,300	49,868
Proved developed reserves- End of year		51,236	28,515	49,300
Proved undeveloped reserves- Beginning of year		15,345	18,900	13,032
Proved undeveloped reserves- End of year			15,345	18,900
Year-end upward revision		12.9
Year-end upward revision due to discoveries and extensions		2
Year-end upward revision due to purchase of additional interest	20.6
Year-end downward revision due to performance		9.8