Charges Associated With Relocation And Restructuring Programs By Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees	$ 18	$ 348	$ 91	$ 10,750
2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees	18	264	20	10,345
Cumulative restructuring charges			10,951
Remaining termination benefits to employees-to be incurred during 2012
2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees		84	71	405
Cumulative restructuring charges			5,938
Remaining termination benefits to employees-to be incurred during 2012
Residential real estate | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees		79	1	244
Cumulative restructuring charges			624
Remaining termination benefits to employees-to be incurred during 2012
Residential real estate | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees				52
Cumulative restructuring charges			1,034
Remaining termination benefits to employees-to be incurred during 2012
Commercial real estate | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees				1,657
Cumulative restructuring charges			1,659
Remaining termination benefits to employees-to be incurred during 2012
Commercial real estate | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees				(3)
Cumulative restructuring charges			43
Remaining termination benefits to employees-to be incurred during 2012
Rural land sales | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees			1	199
Cumulative restructuring charges			209
Remaining termination benefits to employees-to be incurred during 2012
Rural land sales | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees				(12)
Cumulative restructuring charges			769
Remaining termination benefits to employees-to be incurred during 2012
Forestry | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees		77		77
Cumulative restructuring charges			77
Remaining 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 termination benefits to employees-to be incurred during 2012
Other | 2011 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees	18	108	18	8,168
Cumulative restructuring charges			8,382
Remaining termination benefits to employees-to be incurred during 2012
Other | 2010 Restructuring And Relocation Program
Restructuring Cost and Reserve [Line Items]
Termination and relocation benefits to employees		84	71	368
Cumulative restructuring charges			3,899
Remaining termination benefits to employees-to be incurred during 2012