EMPLOYEE BENEFITS (Fair Value of Plan Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Oil and gas royalty interests | Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of the year	$ 198		$ 161
Actual return on plan assets	119		66
Purchases, sales, and settlements (net)	(179)		(29)
Transfers in and/or out of Level 3	0		0
Fair value of plan assets at the end of the year	138		198
Pension Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of the year	25,957		29,609
Actual return on plan assets	4,048		(1,566)
Retiree contributions	0		0
Employer contribution	980		1,139
Benefits paid	(3,194)		(3,225)
Fair value of plan assets at the end of the year	27,791		25,957
Pension Plans | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	17,274		16,078
Pension Plans | Using Significant Other Observable Inputs (Level 2)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	10,379		9,681
Pension Plans | Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	138		198
Pension Plans | Oil and gas royalty interests
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	138	[1]	198	[1]
Pension Plans | Oil and gas royalty interests | Using Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	138	[1]	198	[1]
Postretirement Benefits Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of the year	0		0
Actual return on plan assets	0		0
Retiree contributions	57		66
Employer contribution	562		713
Benefits paid	(619)		(779)
Fair value of plan assets at the end of the year	0		0
Investment funds - equities: | Pension Plans | Research equity portfolio
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	10,379	[2]	9,681	[2]
Investment funds - equities: | Pension Plans | Research equity portfolio | Using Significant Other Observable Inputs (Level 2)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	10,379	[2]	9,681	[2]
Investment funds - equities: | Pension Plans | International stock funds
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	10,479	[3]	10,363	[3]
Investment funds - equities: | Pension Plans | International stock funds | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	10,479	[3]	10,363	[3]
Fixed Income Funds | Pension Plans | Short-term fund
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	1,994	[4]	1,549	[4]
Fixed Income Funds | Pension Plans | Short-term fund | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	1,994	[4]	1,549	[4]
Fixed Income Funds | Pension Plans | Bond fund
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	4,801	[5]	4,166	[5]
Fixed Income Funds | Pension Plans | Bond fund | Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at the end of the year	$ 4,801	[5]	$ 4,166	[5]

[1] The oil and gas royalty interests are valued at their estimated discounted future cash flows, which approximate fair value.

[2] This investment fund’s assets are primarily large capitalization U.S. equities. The investment approach of this fund, which typically holds 110 - 130 securities, focuses on diversifying the investment portfolio by delegating the equity selection process to research analysts with expertise in their respective industries. Industry weights are kept similar to those of the S&P 500 Index. As of December 31, 2012, the sector weighting of this fund was comprised of the following: information technology (18%), financials (16%), consumer discretionary (14%), health care (13%), energy (11%), consumer staples (11%), and other (17%). The fair value of this investment fund was determined based on the net asset value per unit provided by the investee. Forest performs procedures to validate the net asset value per unit provided by the investee. Such procedures include verifying a sample of the net asset values of the underlying securities, which are directly observable in the marketplace.

[3] These three investment funds seek long-term growth of principal and income by investing primarily in diversified portfolios of equity securities issued by foreign, medium-to-large companies in international markets including emerging markets. The first fund typically holds 50 - 100 securities and seeks to invest in solid, well-established global leaders with emphasis on strong corporate governance, positive future growth opportunities, and growing return on capital. As of December 31, 2012, the sector weighting of this fund, which seeks diversification across regions, countries, and market sectors, was comprised of the following: financials (25%), health care (16%), consumer discretionary (13%), information technology (12%), and other (34%). The second fund seeks to obtain growth through long-term appreciation of its holdings, selecting investments based upon their current fundamentals. As of December 31, 2012, the sector weighting of this fund, which invests in Asian (excluding Japanese) growth equities with a focus on domestic demand growth rather than an export orientation, was comprised of the following: financials (32%), information technology (15%), consumer staples (14%), consumer discretionary (12%), and other (27%). The third fund seeks to deliver equity-like returns with significantly less volatility by investing in emerging markets equity securities. As of December 31, 2012, the sector weighting of this fund, which holds approximately 80 positions across the portfolio, with country allocations not exceeding 25%, was comprised of the following: information technology (19%), financials (18%), energy (17%), materials (15%), and other (31%). The fair value of these investment funds was determined based on the funds’ net asset values per unit, which are directly observable in the marketplace.

[4] This investment fund’s assets are high-quality money market instruments and short-term fixed income securities. This fund is actively managed as an enhanced cash strategy, seeking to derive excess returns versus money market fund indices by capturing term, transactional liquidity, credit, and volatility premiums. As of December 31, 2012, the sector weighting of this fund was comprised of the following: government related (33%), investment grade (29%), mortgage (13%), and other (25%). The fair value of this investment fund was determined based on the fund’s net asset value per unit, which is directly observable in the marketplace.

[5] These two investment funds consist of diversified portfolios of bonds. The first fund’s main investments are intermediate maturity fixed income securities with a duration between three and six years, with a maximum of 10% of the portfolio being invested in securities below Baa grade, and up to 30% of the portfolio being invested in non-U.S. dollar denominated securities. As of December 31, 2012, the sector weighting of this fund was comprised of the following: mortgage (40%), government-related (25%), non-U.S. dollar developed market (11%), investment grade (10%), and other (14%). The second fund seeks to deliver equity-like returns with significantly less volatility by investing in emerging markets debt securities. As of December 31, 2012, the sector weighting of this fund, which holds approximately 80 positions across the portfolio, with country allocations not exceeding 25%, was comprised of the following: sovereign-local (41%), inflation linked (30%), corporates (22%), and sovereign U.S. dollar denominated (7%). The fair value of these investment funds was determined based on the funds’ net asset values per unit, which are directly observable in the marketplace.