STOCK-BASED COMPENSATION (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended					3 Months Ended								3 Months Ended				3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011	Mar. 31, 2012 Stock Options	Mar. 31, 2011 Stock Options	Mar. 31, 2012 Restricted Stock	Mar. 31, 2011 Restricted Stock	Mar. 31, 2012 Performance Units		Mar. 31, 2011 Performance Units	Mar. 12, 2012 Performance Units	Mar. 31, 2012 Phantom Stock Units		Mar. 31, 2011 Phantom Stock Units	Mar. 31, 2012 Cash-based long-term incentive award	Mar. 31, 2012 Time-based component of cash-based long-term incentive award	Mar. 31, 2012 Performance-based component of cash-based long-term incentive award	Mar. 31, 2012 Employee Stock Purchase Plan	Mar. 31, 2011 Employee Stock Purchase Plan
Stock-based compensation
Total stock-based compensation costs	$ 5,921	[1],[2]	$ 7,759	[1],[2]		$ 0	$ 163	$ 3,776	$ 6,369	$ 1,212		$ 639		$ 933		$ 588				$ 100	$ 100
Less: stock-based compensation costs capitalized	(2,597)	[1],[2]	(3,041)	[1],[2]		0	(71)	(1,708)	(2,591)	(390)		(179)		(499)		(200)
Stock-based compensation costs expensed	3,324	[1],[2]	4,718	[1],[2]		0	92	2,068	3,778	822		460		434		388
Unamortized stock-based compensation costs	45,991	[1],[2]				0		23,703		13,197				9,091	[3]		500
Weighted average amortization period remaining (in years)	2.0	[1],[2]				0.0		2.1		2.1				1.7
Period after which cash payment will be made dependent on change in value of entity's common stock for Cash-Based Long-term Incentive Award (in years)																		3	3
Period for which Change in Fair Value is Measured for Cash-Based Long-term Incentive Award (in years)																		3	3
Stock option activity
Options outstanding at beginning of period (in shares)	1,766,587
Granted (in shares)	0
Exercised (in shares)	0
Cancelled (in shares)	(6,776)
Options outstanding at end of period (in shares)	1,759,811
Stock Options, Weighted Average Exercise Price
Options outstanding, beginning of period (in dollars per share)	$ 14.55
Granted (in dollars per share)	$ 0.00
Exercised (in dollars per share)	$ 0.00
Cancelled (in dollars per share)	$ 17.29
Options outstanding, end of period (in dollars per share)	$ 14.54
Stock Options, Aggregate Intrinsic Value
Aggregate intrinsic value for stock options at beginning of the period	2,731	[4]
Aggregate intrinsic value for stock options exercised	0	[4]
Aggregate intrinsic value for stock options at end of the period	1,540	[4]
Stock Options, Number of Options Exercisable
Options outstanding, exercisable number (in shares)	1,759,811				1,766,587
Share-based compensation plan activity
Unvested stock, beginning of period (in shares)								2,474,112		655,120	[5]			1,238,817	[6]
Awarded (in shares)								547,025		511,500	[5]			0	[6]
Vested (in shares)								(19,980)		0	[5]			(8,468)	[6]
Forfeited (in shares)								(18,735)		0	[5]			(3,995)	[6]
Unvested stock, end of period (in shares)								2,982,422		1,166,620	[5]			1,226,354	[6]
Weighted Average Grant Date Fair Value
Unvested at beginning of period (in dollars per share)								$ 24.00		$ 19.50				$ 14.32
Awarded (in dollars per share)								$ 12.46		$ 14.70				$ 0.00
Vested (in dollars per share)								$ 23.71		$ 0.00				$ 15.71
Forfeited (in dollars per share)								$ 23.86		$ 0.00				$ 16.44
Unvested at end of period (in dollars per share)								$ 21.89		$ 17.39				$ 14.30
Vest Date Fair Value
Vested, Vest Date fair Value								$ 246		$ 0				$ 105
Number of shares of common stock to be received for each performance unit (in shares)													1
Actual number of shares deliverable for each performance unit awarded, low end of range (as a percent)													0.00%
Actual number of shares deliverable for each performance unit awarded, high end of range (as a percent)													200.00%
Performance period (in months)										36 months
Unvested units that can be settled in cash, shares of common stock, or a combination of both (in shares)														6,080
Unvested units that can only be settled in cash (in shares)														1,220,274
Vested units settled in cash (in shares)														8,468

[1] The Company also maintains an employee stock purchase plan (which is not included in the table) under which $.1 million of compensation cost was recognized in each of the three-month periods ended March 31, 2012 and 2011.

[2] In addition to the compensation costs set forth in the table above, in June 2011 and March 2012 the Company granted cash-based long-term incentive awards under which a negligible amount of compensation cost was recognized during the three months ended March 31, 2012 due primarily to a reduction in Forest’s common stock price, and under which $.5 million remains as unamortized stock-based compensation costs at March 31, 2012. The awards are comprised of time-based and performance-based components. Under the time-based component, a cash payment will be made three years after the date of grant dependent on the change in the market value of Forest’s common stock during the three-year period, and under the performance-based component, a cash payment will be made three years after the date of grant dependent on the total shareholder return on Forest’s common stock in comparison to that of a peer group during the three-year period.

[3] Based on the closing price of Forest’s common stock on March 31, 2012.

[4] The intrinsic value of a stock option is the amount by which the market value of the underlying stock, as of the date outstanding or exercised, exceeds the exercise price of the option.

[5] Forest granted 511,500 performance units on March 12, 2012, with a grant date fair value of $14.70 each. Under the terms of the award agreements, each performance unit represents a contractual right to receive one share of Forest’s common stock; provided that the actual number of shares that may be deliverable under an award will range from 0% to 200% of the number of performance units awarded, depending on Forest’s relative total shareholder return in comparison to an identified peer group during the thirty-six-month performance period ending on February 28, 2015.

[6] Of the unvested phantom stock units at March 31, 2012, 6,080 units can be settled in cash, shares of common stock, or a combination of both, while the remaining 1,220,274 units can only be settled in cash. The phantom stock units have been accounted for as a liability within the Condensed Consolidated Financial Statements. All of the 8,468 phantom stock units that vested during the three months ended March 31, 2012 were settled in cash.