CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues:
Oil, natural gas, and natural gas liquids sales	$ 156,014			$ 174,012	$ 450,609	$ 526,915
Interest and other	54			109	123	939
Equity earnings in subsidiaries	0			0	0	0
Total revenues	156,068			174,121	450,732	527,854
Costs, expenses, and other:
Lease operating expenses	27,426			23,480	82,167	70,593
Other production expenses	12,422			11,123	38,102	42,450
General and administrative	13,416			19,942	45,221	49,122
Depreciation, depletion, and amortization	73,845			54,323	213,802	155,227
Ceiling test write-down of oil and natural gas properties	329,957	349,000	34,800	0	713,750	0
Impairment of properties	79,529			0	79,529	0
Interest expense	36,223			37,225	103,932	113,081
Realized and unrealized losses (gains) on derivative instruments, net	22,795			(65,961)	(40,744)	(70,632)
Other, net	11,727			(177)	42,102	12,280
Total costs, expenses, and other	607,340			79,955	1,277,861	372,121
Earnings (loss) from continuing operations before income taxes	(451,272)			94,166	(827,129)	155,733
Income tax	7,280			34,556	175,269	76,940
Net earnings (loss) from continuing operations	(458,552)			59,610	(1,002,398)	78,793
Net earnings from discontinued operations	0			28,108	0	44,569
Net earnings (loss)	(458,552)			87,718	(1,002,398)	123,362
Less: net earnings attributable to noncontrolling interest	0			4,923	0	4,987
Net earnings (loss) attributable to Forest Oil Corporation common shareholders	(458,552)			82,795	(1,002,398)	118,375
Comprehensive income (loss)	(458,367)			49,577	(1,001,840)	95,910
Parent Company
Revenues:
Oil, natural gas, and natural gas liquids sales	119,588			128,849	326,209	382,211
Interest and other	1,694			348	3,381	1,696
Equity earnings in subsidiaries	(73,712)			39,093	(81,311)	90,828
Total revenues	47,570			168,290	248,279	474,735
Costs, expenses, and other:
Lease operating expenses	23,115			20,218	69,087	60,487
Other production expenses	12,546			11,816	36,937	37,160
General and administrative	12,341			18,672	42,300	45,726
Depreciation, depletion, and amortization	55,978			40,675	157,381	115,738
Ceiling test write-down of oil and natural gas properties	324,155			0	673,131	0
Impairment of properties	0			0	0	0
Interest expense	36,224			37,225	103,932	113,081
Realized and unrealized losses (gains) on derivative instruments, net	17,883			(73,757)	(33,044)	(77,929)
Other, net	8,692			(1,895)	35,259	8,354
Total costs, expenses, and other	490,934			52,954	1,084,983	302,617
Earnings (loss) from continuing operations before income taxes	(443,364)			115,336	(836,704)	172,118
Income tax	15,188			27,618	165,694	48,756
Net earnings (loss) from continuing operations	(458,552)			87,718	(1,002,398)	123,362
Net earnings from discontinued operations	0			0	0	0
Net earnings (loss)	(458,552)			87,718	(1,002,398)	123,362
Less: net earnings attributable to noncontrolling interest	0			0	0	0
Net earnings (loss) attributable to Forest Oil Corporation common shareholders	(458,552)			87,718	(1,002,398)	123,362
Comprehensive income (loss)	(458,367)			49,577	(1,001,840)	95,910
Guarantor Subsidiary
Revenues:
Oil, natural gas, and natural gas liquids sales	36,002			44,529	123,093	142,775
Interest and other	1,278			76	1,850	138
Equity earnings in subsidiaries	0			0	0	0
Total revenues	37,280			44,605	124,943	142,913
Costs, expenses, and other:
Lease operating expenses	4,195			3,161	12,774	9,789
Other production expenses	(165)			(735)	1,026	5,188
General and administrative	689			881	2,040	2,094
Depreciation, depletion, and amortization	17,433			13,251	55,116	38,193
Ceiling test write-down of oil and natural gas properties	0			0	0	0
Impairment of properties	0			0	0	0
Interest expense	706			(159)	894	(351)
Realized and unrealized losses (gains) on derivative instruments, net	4,848			7,780	(7,603)	7,282
Other, net	96			186	293	165
Total costs, expenses, and other	27,802			24,365	64,540	62,360
Earnings (loss) from continuing operations before income taxes	9,478			20,240	60,403	80,553
Income tax	(842)			7,825	19,075	30,497
Net earnings (loss) from continuing operations	10,320			12,415	41,328	50,056
Net earnings from discontinued operations	0			0	0	0
Net earnings (loss)	10,320			12,415	41,328	50,056
Less: net earnings attributable to noncontrolling interest	0			0	0	0
Net earnings (loss) attributable to Forest Oil Corporation common shareholders	10,320			12,415	41,328	50,056
Comprehensive income (loss)	10,320			12,415	41,328	50,056
Combined Non-Guarantor Subsidiaries
Revenues:
Oil, natural gas, and natural gas liquids sales	424			634	1,307	1,929
Interest and other	0			0	0	0
Equity earnings in subsidiaries	0			0	0	0
Total revenues	424			634	1,307	1,929
Costs, expenses, and other:
Lease operating expenses	116			101	306	317
Other production expenses	41			42	139	102
General and administrative	386			389	881	1,302
Depreciation, depletion, and amortization	434			397	1,305	1,296
Ceiling test write-down of oil and natural gas properties	5,802			0	40,619	0
Impairment of properties	79,529			0	79,529	0
Interest expense	2,211			474	4,214	1,246
Realized and unrealized losses (gains) on derivative instruments, net	64			16	(97)	15
Other, net	2,939			1,532	6,550	3,761
Total costs, expenses, and other	91,522			2,951	133,446	8,039
Earnings (loss) from continuing operations before income taxes	(91,098)			(2,317)	(132,139)	(6,110)
Income tax	(7,066)			(887)	(9,500)	(2,313)
Net earnings (loss) from continuing operations	(84,032)			(1,430)	(122,639)	(3,797)
Net earnings from discontinued operations	0			28,108	0	44,569
Net earnings (loss)	(84,032)			26,678	(122,639)	40,772
Less: net earnings attributable to noncontrolling interest	0			4,923	0	4,987
Net earnings (loss) attributable to Forest Oil Corporation common shareholders	(84,032)			21,755	(122,639)	35,785
Comprehensive income (loss)	(84,032)			26,678	(122,639)	40,772
Eliminations
Revenues:
Oil, natural gas, and natural gas liquids sales	0			0	0	0
Interest and other	(2,918)			(315)	(5,108)	(895)
Equity earnings in subsidiaries	73,712			(39,093)	81,311	(90,828)
Total revenues	70,794			(39,408)	76,203	(91,723)
Costs, expenses, and other:
Lease operating expenses	0			0	0	0
Other production expenses	0			0	0	0
General and administrative	0			0	0	0
Depreciation, depletion, and amortization	0			0	0	0
Ceiling test write-down of oil and natural gas properties	0			0	0	0
Impairment of properties	0			0	0	0
Interest expense	(2,918)			(315)	(5,108)	(895)
Realized and unrealized losses (gains) on derivative instruments, net	0			0	0	0
Other, net	0			0	0	0
Total costs, expenses, and other	(2,918)			(315)	(5,108)	(895)
Earnings (loss) from continuing operations before income taxes	73,712			(39,093)	81,311	(90,828)
Income tax	0			0	0	0
Net earnings (loss) from continuing operations	73,712			(39,093)	81,311	(90,828)
Net earnings from discontinued operations	0			0	0	0
Net earnings (loss)	73,712			(39,093)	81,311	(90,828)
Less: net earnings attributable to noncontrolling interest	0			0	0	0
Net earnings (loss) attributable to Forest Oil Corporation common shareholders	73,712			(39,093)	81,311	(90,828)
Comprehensive income (loss)	$ 73,712			$ (39,093)	$ 81,311	$ (90,828)