INCOME TAXES (Income Before Income Tax, Domestic and Foreign) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings (loss) from continuing operations before income taxes
United States federal																	$ 65,167	$ (1,013,801)	$ 188,421
Foreign																	8,050	(101,693)	(1,026)
Earnings (loss) from continuing operations before income taxes	$ 105,974	[1]	$ 1,627	[1]	$ 33,227	[1]	$ (67,611)	[1]	$ (288,365)	[1]	$ (451,272)	[1]	$ (344,099)	[1]	$ (31,758)	[1]	$ 73,217	$ (1,115,494)	$ 187,395

[1] Earnings (loss) before income taxes and net earnings (loss) have been impacted by non-cash ceiling test write-downs in every quarter of 2012 and the fourth quarter of 2013, as discussed in Note 1, and are also subject to large fluctuations due to Forest’s election not to use cash flow hedge accounting for derivative instruments as discussed in Note 9. Also impacting the fourth quarter of 2013 is a $193.0 million net gain on the Panhandle divestiture, as discussed in Note 2.