Charges Associated With Relocation And Restructuring Programs By Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees	$ 18	$ 5,926	$ 73	$ 10,402
2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees		5,873	2	10,080
Cumulative restructuring charges			10,933
Remaining one-time termination benefits to employees - to be incurred during 2012
2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees	18	53	71	322
Cumulative restructuring charges			5,938
Remaining one-time termination benefits to employees - to be incurred during 2012
Residential real estate | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees		164	1	164
Cumulative restructuring charges			624
Remaining one-time termination benefits to employees - to be incurred during 2012
Residential real estate | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees	(22)	9		52
Cumulative restructuring charges			1,034
Remaining one-time termination benefits to employees - to be incurred during 2012
Commercial real estate | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees		1,657		1,657
Cumulative restructuring charges			1,659
Remaining one-time termination benefits to employees - to be incurred during 2012
Commercial real estate | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees				(3)
Cumulative restructuring charges			43
Remaining one-time termination benefits to employees - to be incurred during 2012
Rural land sales | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees		199	1	199
Cumulative restructuring charges			209
Remaining one-time termination benefits to employees - to be incurred during 2012
Rural land sales | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees				(12)
Cumulative restructuring charges			769
Remaining one-time termination benefits to employees - to be incurred during 2012
Forestry | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative restructuring charges			77
Remaining one-time termination benefits to employees - to be incurred during 2012
Forestry | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
Cumulative restructuring charges			193
Remaining one-time termination benefits to employees - to be incurred during 2012
Other | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees		3,853		8,060
Cumulative restructuring charges			8,364
Remaining one-time termination benefits to employees - to be incurred during 2012
Other | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
One-time termination and relocation benefits to employees	40	44	71	285
Cumulative restructuring charges			3,899
Remaining one-time termination benefits to employees - to be incurred during 2012