Supplementary Oil and Gas Disclosure (Unaudited) - Reserves (Details)	12 Months Ended
	Dec. 31, 2013 MBbls	Dec. 31, 2012 MBbls	Dec. 31, 2011 MBbls	Dec. 31, 2013 MBbls	Dec. 31, 2010 MBbls
Proved developed and undeveloped reserves as of:
Beginning balance	566,000	652,000	619,000	612,000
Revisions of previous estimates	14,000	(91,000)	(48,000)
Extensions, discoveries and other additions	80,000	86,000	142,000
Purchase of properties	2,000	0	9,000
Sales of properties	(1,000)	(30,000)	(20,000)
Production	(49,000)	(51,000)	(50,000)
Proved developed reserves as of:
Proved developed reserves	337,000	298,000	355,000		361,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	275,000	268,000	297,000		258,000
Natural Gas [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	1,755,000	2,333,000	2,492,000	1,648,000
Revisions of previous estimates	(166,000)	(527,000)	(175,000)
Extensions, discoveries and other additions	187,000	181,000	280,000
Purchase of properties	1,000	1,000	9,000
Sales of properties	(5,000)	(80,000)	(91,000)
Production	(124,000)	(153,000)	(182,000)
Proved developed reserves as of:
Proved developed reserves	1,055,000	1,042,000	1,409,000		1,505,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	593,000	713,000	924,000		987,000
Oil [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	237,000	247,000	198,000	270,000
Revisions of previous estimates	28,000	(11,000)	(26,000)
Extensions, discoveries and other additions	27,000	38,000	91,000
Purchase of properties	1,000	0	7,000
Sales of properties	0	(15,000)	(5,000)
Production	(23,000)	(22,000)	(18,000)
Proved developed reserves as of:
Proved developed reserves	127,000	110,000	110,000		107,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	143,000	127,000	137,000		91,000
natural gas liquids
Proved developed and undeveloped reserves as of:
Beginning balance	37,000	16,000	6,000	68,000
Revisions of previous estimates	14,000	9,000	7,000
Extensions, discoveries and other additions	22,000	17,000	5,000
Purchase of properties	0	0	0
Sales of properties	0	(2,000)	0
Production	(5,000)	(3,000)	(2,000)
Proved developed reserves as of:
Proved developed reserves	35,000	15,000	10,000		3,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	33,000	22,000	6,000		3,000
Domestic [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	532,000	608,000	585,000	576,000
Revisions of previous estimates	5,000	(92,000)	(46,000)
Extensions, discoveries and other additions	78,000	86,000	123,000
Purchase of properties	2,000	0	9,000
Sales of properties	(1,000)	(30,000)	(20,000)
Production	(40,000)	(40,000)	(43,000)
Proved developed reserves as of:
Proved developed reserves	322,000	280,000	332,000		341,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	254,000	252,000	276,000		244,000
Domestic [Member] | Natural Gas [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	1,755,000	2,329,000	2,492,000	1,648,000
Revisions of previous estimates	(166,000)	(525,000)	(175,000)
Extensions, discoveries and other additions	187,000	181,000	276,000
Purchase of properties	1,000	1,000	9,000
Sales of properties	(5,000)	(80,000)	(91,000)
Production	(124,000)	(151,000)	(182,000)
Proved developed reserves as of:
Proved developed reserves	1,055,000	1,042,000	1,405,000		1,505,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	593,000	713,000	924,000		987,000
Domestic [Member] | Oil [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	203,000	204,000	164,000	234,000
Revisions of previous estimates	19,000	(13,000)	(24,000)
Extensions, discoveries and other additions	25,000	38,000	73,000
Purchase of properties	1,000	0	7,000
Sales of properties	0	(15,000)	(5,000)
Production	(14,000)	(11,000)	(11,000)
Proved developed reserves as of:
Proved developed reserves	112,000	92,000	88,000		87,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	122,000	111,000	116,000		77,000
Domestic [Member] | natural gas liquids
Proved developed and undeveloped reserves as of:
Beginning balance	37,000	16,000	6,000	68,000
Revisions of previous estimates	14,000	9,000	7,000
Extensions, discoveries and other additions	22,000	17,000	5,000
Purchase of properties	0	0	0
Sales of properties	0	(2,000)	0
Production	(5,000)	(3,000)	(2,000)
Proved developed reserves as of:
Proved developed reserves	35,000	15,000	10,000		3,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	33,000	22,000	6,000		3,000
Malaysia [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	15,000	24,000	28,000	11,000
Revisions of previous estimates	2,000	1,000	(2,000)
Extensions, discoveries and other additions	2,000	0	4,000
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	(8,000)	(10,000)	(6,000)
Proved developed reserves as of:
Proved developed reserves	11,000	14,000	18,000		15,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	0	1,000	6,000		13,000
Malaysia [Member] | Natural Gas [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	0	4,000	0	0
Revisions of previous estimates	0	(2,000)	0
Extensions, discoveries and other additions	0	0	4,000
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	0	(2,000)	0
Proved developed reserves as of:
Proved developed reserves	0	0	4,000		0
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	0	0	0		0
Malaysia [Member] | Oil [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	15,000	23,000	28,000	11,000
Revisions of previous estimates	2,000	2,000	(2,000)
Extensions, discoveries and other additions	2,000	0	3,000
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	(8,000)	(10,000)	(6,000)
Proved developed reserves as of:
Proved developed reserves	11,000	14,000	17,000		15,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	0	1,000	6,000		13,000
Malaysia [Member] | natural gas liquids
Proved developed and undeveloped reserves as of:
Beginning balance	0	0	0	0
Revisions of previous estimates	0	0	0
Extensions, discoveries and other additions	0	0	0
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	0	0	0
Proved developed reserves as of:
Proved developed reserves	0	0	0		0
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	0	0	0		0
China [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	19,000	20,000	6,000	25,000
Revisions of previous estimates	7,000	0	0
Extensions, discoveries and other additions	0	0	15,000
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	(1,000)	(1,000)	(1,000)
Proved developed reserves as of:
Proved developed reserves	4,000	4,000	5,000		5,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	21,000	15,000	15,000		1,000
China [Member] | Natural Gas [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	0	0	0	0
Revisions of previous estimates	0	0	0
Extensions, discoveries and other additions	0	0	0
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	0	0	0
Proved developed reserves as of:
Proved developed reserves	0	0	0		0
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	0	0	0		0
China [Member] | Oil [Member]
Proved developed and undeveloped reserves as of:
Beginning balance	19,000	20,000	6,000	25,000
Revisions of previous estimates	7,000	0	0
Extensions, discoveries and other additions	0	0	15,000
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	(1,000)	(1,000)	(1,000)
Proved developed reserves as of:
Proved developed reserves	4,000	4,000	5,000		5,000
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	21,000	15,000	15,000		1,000
China [Member] | natural gas liquids
Proved developed and undeveloped reserves as of:
Beginning balance	0	0	0	0
Revisions of previous estimates	0	0	0
Extensions, discoveries and other additions	0	0	0
Purchase of properties	0	0	0
Sales of properties	0	0	0
Production	0	0	0
Proved developed reserves as of:
Proved developed reserves	0	0	0		0
Proved undeveloped reserves as of:
Proved Undeveloped Reserves	0	0	0		0