Debt Schedule of Long-Term Debt Instruments (Details) (USD $)				12 Months Ended						12 Months Ended												12 Months Ended			12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2011 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]		Dec. 31, 2010 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]		Dec. 31, 2009 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]	Oct. 01, 2007 Senior Exchangeable Notes due 2012 at a fixed interest rate of 3.75% [Member]	Dec. 31, 2011 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]		Dec. 31, 2010 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]		Dec. 31, 2009 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]	Aug. 01, 2009 Senior Exchangeable Notes due 2015 at a fixed interest rate of 4.50% [Member]	Dec. 31, 2011 Installment note due 2011 at a fixed interest rate of 8.49% (retired in 2011) [Member]	Dec. 31, 2010 Installment note due 2011 at a fixed interest rate of 8.49% (retired in 2011) [Member]	Dec. 31, 2011 Installment note due 2014 at a fixed interest rate of 8.64% [Member]	Dec. 31, 2010 Installment note due 2014 at a fixed interest rate of 8.64% [Member]	Dec. 31, 2011 Secured Mortgage Notes Assumed with Timberland Acquisition [Member]		Dec. 31, 2011 Bonds [Member]	Dec. 31, 2010 Bonds [Member]	Dec. 31, 2010 March 2015 Term Loan [Member]	Dec. 31, 2011 April 2011 Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Debt Maturing in Less than One Year, Classified as Long-term Debt				$ 295,000,000
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	323,110,000	[1]
Long-term Debt, Maturities, Repayments of Principal in Year Two	0
Long-term Debt, Maturities, Repayments of Principal in Year Three	112,500,000
Long-term Debt, Maturities, Repayments of Principal in Year Four	172,500,000
Long-term Debt, Maturities, Repayments of Principal in Year Five	150,000,000
Long-term Debt, Maturities, Repayments of Principal after Year Five	99,000,000
Long-term Debt	847,339,000		768,160,000	294,622,000	[1]	288,135,000	[1]			163,525,000	[1]	161,358,000	[1]				93,057,000	112,500,000	112,500,000	88,582,000	[2]	38,110,000	38,110,000	75,000,000	150,000,000
Long-term Debt, Current Maturities	(28,110,000)		(93,057,000)
Long-term Debt, Excluding Current Maturities	819,229,000		675,103,000
Long-term Debt, Gross	$ 857,110,000
Debt Instrument, Interest Rate at Period End																								3.02%
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum																						1.65%			1.35%
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimum																						1.60%			1.34%
Debt Instrument, Interest Rate, Stated Percentage				3.75%					3.75%	4.50%					4.50%	8.49%		8.64%		4.35%
Debt Instrument, Convertible, Effective Interest Rate				6.21%		6.21%		6.21%		6.21%		6.21%		6.21%

[1] Our Senior Exchangeable Notes maturing in 2012 were discounted by $5.4 million and $11.9 million as of December 31, 2011 and 2010, respectively, but upon maturity the liability will be $300.0 million. $295 million of these notes are included in long-term debt due to the ability and intent of the company to refinance them on a long-term basis. See the paragraph below regarding available borrowings under the revolving credit facility. Our Senior Exchangeable Notes maturing in 2015 were discounted by $9.0 million and $11.1 million as of December 31, 2011 and 2010, but upon maturity the liability will be $172.5 million.

[2] The mortgage notes due in 2017 were recorded at fair value, which increased the book value by $4.6 million as of December 31, 2011. Upon maturity the liability will be $84.0 million.