DISCONTINUED OPERATIONS (Details) (USD $)	0 Months Ended		3 Months Ended			6 Months Ended
	Sep. 30, 2011	Jun. 01, 2011	Jun. 30, 2012	Sep. 30, 2011	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Net [Abstract]
Net earnings (loss) attributable to Forest Oil Corporation			$ (511,173,000)		$ 38,910,000	$ (543,846,000)	$ 35,580,000
Transfers from (to) noncontrolling interest
Increase in Forest Oil Corporation's capital surplus for sale of 15 million Lone Pine Resources Inc. common shares					112,879,000		112,879,000
Change from net earnings attributable to Forest Oil Corporation and transfers from (to) noncontrolling interest					151,789,000		148,459,000
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Total revenues					51,263,000		87,536,000
Production expenses					13,993,000		26,448,000
General and administrative					2,377,000		5,591,000
Depreciation, depletion, and amortization					20,962,000		39,981,000
Interest expense					1,155,000		1,239,000
Unrealized gains on derivative instruments, net					(5,130,000)		(5,130,000)
Realized foreign currency exchange gains					(33,892,000)		(33,892,000)
Unrealized foreign currency exchange gains, net					36,360,000		28,540,000
Other, net					617,000		691,000
Earnings from discontinued operations before tax					14,821,000		24,068,000
Income tax					4,951,000		7,607,000
Net earnings from discontinued operations			0		9,870,000	0	16,461,000
Lone Pine IPO
Percentage of subsidiary common stock sold in initial public offering (as a percent)		18.00%
Dividend Tax Payable, Foreign							28,900,000
Sale of Stock, Consideration Received on Transaction		178,000,000
Sale of Stock Partial Consideration Received on Transaction Used to Pay Consideration to Parent		29,200,000
Payment of Intercompany Note and Advances and Accrued Interest		$ 400,500,000
Percentage of subsidiary stock distributed in spin-off (as a percent)	82.00%
Common stock conversion ratio (as a ratio)				0.61248511
Sale of Stock, Number of Shares Issued in Transaction		15,000,000