CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended																9 Months Ended	12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Oil, natural gas, and natural gas liquids sales	$ 154,914		$ 156,014		$ 135,694		$ 158,901		$ 176,616		$ 174,012		$ 186,593		$ 166,310			$ 605,523	$ 703,531	$ 707,692
Interest and other																		136	1,026	989
Equity earnings in subsidiaries																		0	0	0
Total revenues																		605,659	704,557	708,681
Costs, expenses, and other:
Lease operating expenses																		108,027	99,158	92,394
Other production expenses																		48,882	54,360	56,898
General and administrative																		59,262	65,105	64,886
Depreciation, depletion, and amortization																		280,458	219,684	187,973
Ceiling test write-down of oil and natural gas properties																		992,404	0	0
Impairment of properties																		79,529	0	0
Interest expense																		141,831	149,755	149,891
Realized and unrealized (gains) losses on derivative instruments, net																		(72,646)	(88,064)	(150,132)
Other, net																		83,406	17,164	7,339
Total costs, expenses, and other																		1,721,153	517,162	409,249
Earnings (loss) from continuing operations before income taxes	(288,365)	[1]	(451,272)	[1]	(344,099)	[1]	(31,758)	[1]	31,662	[1]	94,166	[1]	75,861	[1]	(14,294)	[1]		(1,115,494)	187,395	299,432
Income tax																		173,437	89,135	109,770
Net earnings (loss) from continuing operations																		(1,288,931)	98,260	189,662
Net earnings from discontinued operations																	44,569	0	44,569	37,859
Net earnings (loss)	(286,533)	[1]	(458,552)	[1]	(511,173)	[1]	(32,673)	[1]	19,467	[1]	87,718	[1]	38,974	[1]	(3,330)	[1]		(1,288,931)	142,829	227,521
Less: net earnings attributable to noncontrolling interest																		0	4,987	0
Net earnings (loss) attributable to Forest Oil Corporation common shareholders									19,467	[1],[2]	82,795	[1],[2]	38,910	[1],[2]	(3,330)	[1],[2]	118,375	(1,288,931)	137,842	227,521
Net earnings (loss)	(286,533)	[1]	(458,552)	[1]	(511,173)	[1]	(32,673)	[1]	19,467	[1]	87,718	[1]	38,974	[1]	(3,330)	[1]		(1,288,931)	142,829	227,521
Other comprehensive income (loss):
Foreign currency translation (losses) gains																		0	(27,852)	15,153
Defined benefit postretirement plans losses, net of tax																		(2,242)	(6,669)	(746)
Total other comprehensive income (loss)																		(2,242)	(34,521)	14,407
Total comprehensive income (loss)																		(1,291,173)	108,308	241,928
Less: total comprehensive loss attributable to noncontrolling interest																		0	(1,330)	0
Total comprehensive income (loss) attributable to Forest Oil Corporation common shareholders																		(1,291,173)	109,638	241,928
Parent Company
Revenues:
Oil, natural gas, and natural gas liquids sales																		442,034	517,649	479,250
Interest and other																		4,888	3,569	5,504
Equity earnings in subsidiaries																		(71,028)	102,237	138,354
Total revenues																		375,894	623,455	623,108
Costs, expenses, and other:
Lease operating expenses																		91,214	84,117	79,927
Other production expenses																		45,211	47,066	45,318
General and administrative																		54,815	60,855	60,901
Depreciation, depletion, and amortization																		207,622	165,270	130,777
Ceiling test write-down of oil and natural gas properties																		950,157
Impairment of properties																		0
Interest expense																		141,830	149,755	149,891
Realized and unrealized (gains) losses on derivative instruments, net																		(58,123)	(91,221)	(122,389)
Other, net																		73,548	11,386	877
Total costs, expenses, and other																		1,506,274	427,228	345,302
Earnings (loss) from continuing operations before income taxes																		(1,130,380)	196,227	277,806
Income tax																		158,551	53,398	50,285
Net earnings (loss) from continuing operations																		(1,288,931)	142,829	227,521
Net earnings from discontinued operations																			0	0
Net earnings (loss)																			142,829	227,521
Less: net earnings attributable to noncontrolling interest																			0
Net earnings (loss) attributable to Forest Oil Corporation common shareholders																			142,829
Net earnings (loss)																			142,829	227,521
Other comprehensive income (loss):
Foreign currency translation (losses) gains																			0	0
Defined benefit postretirement plans losses, net of tax																		(2,242)	(6,669)	(932)
Total other comprehensive income (loss)																		(2,242)	(6,669)	(932)
Total comprehensive income (loss)																		(1,291,173)	136,160	226,589
Less: total comprehensive loss attributable to noncontrolling interest																			0
Total comprehensive income (loss) attributable to Forest Oil Corporation common shareholders																			136,160
Guarantor Subsidiary
Revenues:
Oil, natural gas, and natural gas liquids sales																		159,578	183,391	225,937
Interest and other																		2,360	5,834	32
Equity earnings in subsidiaries																		0	0	0
Total revenues																		161,938	189,225	225,969
Costs, expenses, and other:
Lease operating expenses																		16,422	14,620	11,974
Other production expenses																		3,383	7,122	11,454
General and administrative																		2,730	2,787	2,408
Depreciation, depletion, and amortization																		70,993	52,692	55,642
Ceiling test write-down of oil and natural gas properties																		0
Impairment of properties																		0
Interest expense																		1,058	4,949	1,381
Realized and unrealized (gains) losses on derivative instruments, net																		(14,275)	3,192	(27,457)
Other, net																		413	238	(456)
Total costs, expenses, and other																		80,724	85,600	54,946
Earnings (loss) from continuing operations before income taxes																		81,214	103,625	171,023
Income tax																		25,428	39,647	62,919
Net earnings (loss) from continuing operations																		55,786	63,978	108,104
Net earnings from discontinued operations																			0	0
Net earnings (loss)																			63,978	108,104
Less: net earnings attributable to noncontrolling interest																			0
Net earnings (loss) attributable to Forest Oil Corporation common shareholders																			63,978
Net earnings (loss)																			63,978	108,104
Other comprehensive income (loss):
Foreign currency translation (losses) gains																			0	0
Defined benefit postretirement plans losses, net of tax																		0	0	0
Total other comprehensive income (loss)																		0	0	0
Total comprehensive income (loss)																		55,786	63,978	108,104
Less: total comprehensive loss attributable to noncontrolling interest																			0
Total comprehensive income (loss) attributable to Forest Oil Corporation common shareholders																			63,978
Combined Non-Guarantor Subsidiaries
Revenues:
Oil, natural gas, and natural gas liquids sales																		3,911	2,491	2,505
Interest and other																		0	0	0
Equity earnings in subsidiaries																		0	0	0
Total revenues																		3,911	2,491	2,505
Costs, expenses, and other:
Lease operating expenses																		391	421	493
Other production expenses																		288	172	126
General and administrative																		1,717	1,463	1,577
Depreciation, depletion, and amortization																		1,843	1,722	1,554
Ceiling test write-down of oil and natural gas properties																		42,247
Impairment of properties																		79,529
Interest expense																		6,055	3,428	3,166
Realized and unrealized (gains) losses on derivative instruments, net																		(248)	(35)	(286)
Other, net																		9,445	5,540	6,918
Total costs, expenses, and other																		141,267	12,711	13,548
Earnings (loss) from continuing operations before income taxes																		(137,356)	(10,220)	(11,043)
Income tax																		(10,542)	(3,910)	(3,434)
Net earnings (loss) from continuing operations																		(126,814)	(6,310)	(7,609)
Net earnings from discontinued operations																			44,569	37,859
Net earnings (loss)																			38,259	30,250
Less: net earnings attributable to noncontrolling interest																			4,987
Net earnings (loss) attributable to Forest Oil Corporation common shareholders																			33,272
Net earnings (loss)																			38,259	30,250
Other comprehensive income (loss):
Foreign currency translation (losses) gains																			(27,852)	15,153
Defined benefit postretirement plans losses, net of tax																		0	0	186
Total other comprehensive income (loss)																		0	(27,852)	15,339
Total comprehensive income (loss)																		(126,814)	10,407	45,589
Less: total comprehensive loss attributable to noncontrolling interest																			(1,330)
Total comprehensive income (loss) attributable to Forest Oil Corporation common shareholders																			11,737
Eliminations
Revenues:
Oil, natural gas, and natural gas liquids sales																		0	0	0
Interest and other																		(7,112)	(8,377)	(4,547)
Equity earnings in subsidiaries																		71,028	(102,237)	(138,354)
Total revenues																		63,916	(110,614)	(142,901)
Costs, expenses, and other:
Lease operating expenses																		0	0	0
Other production expenses																		0	0	0
General and administrative																		0	0	0
Depreciation, depletion, and amortization																		0	0	0
Ceiling test write-down of oil and natural gas properties																		0
Impairment of properties																		0
Interest expense																		(7,112)	(8,377)	(4,547)
Realized and unrealized (gains) losses on derivative instruments, net																		0	0	0
Other, net																		0	0	0
Total costs, expenses, and other																		(7,112)	(8,377)	(4,547)
Earnings (loss) from continuing operations before income taxes																		71,028	(102,237)	(138,354)
Income tax																		0	0	0
Net earnings (loss) from continuing operations																		71,028	(102,237)	(138,354)
Net earnings from discontinued operations																			0	0
Net earnings (loss)																			(102,237)	(138,354)
Less: net earnings attributable to noncontrolling interest																			0
Net earnings (loss) attributable to Forest Oil Corporation common shareholders																			(102,237)
Net earnings (loss)																			(102,237)	(138,354)
Other comprehensive income (loss):
Foreign currency translation (losses) gains																			0	0
Defined benefit postretirement plans losses, net of tax																		0	0	0
Total other comprehensive income (loss)																		0	0	0
Total comprehensive income (loss)																		71,028	(102,237)	(138,354)
Less: total comprehensive loss attributable to noncontrolling interest																			0
Total comprehensive income (loss) attributable to Forest Oil Corporation common shareholders																			$ (102,237)

[1] Earnings (loss) before income taxes, net earnings (loss), and net earnings (loss) attributable to Forest Oil Corporation common shareholders have been impacted by non-cash ceiling test write-downs in every quarter of 2012 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.

[2] Upon completion of Lone Pine’s initial public offering on June 1, 2011, Forest maintained a controlling interest in Lone Pine until it was spun-off on September 30, 2011. As such, during the second and third quarters of 2011, Forest had net earnings attributable to the noncontrolling interest.