Segment Information - Information by Business Segment (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 Segment	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of reportable operating segments									4
Operating revenues	$ 15,676,000	$ 23,947,000	$ 68,164,000	$ 594,086,000	$ 33,868,000	$ 36,827,000	$ 33,788,000	$ 26,773,000	$ 701,873,000	$ 131,256,000	$ 139,396,000
Depreciation, depletion and amortization									8,422,000	9,131,000	10,110,000
Investment income, net									12,691,000	1,498,000	707,000
Interest expense									(8,608,000)	(2,040,000)	(2,820,000)
Income (loss) before equity in loss from unconsolidated affiliates and income taxes:									521,821,000	4,445,000	6,423,000
Payments to Acquire Productive Assets									32,441,000	42,060,000	23,395,000
Assets	1,303,135,000				669,472,000				1,303,135,000	669,472,000
Revenues from RiverTown Sale									43,600,000
Revenues from AgReserves Sale									570,900,000
Interest Income, Other									990,000	234,000	707,000
Impairment losses									0	5,080,000	2,551,000
Pension charges									8,749,000	1,500,000	2,063,000
Residential real estate
Segment Reporting Information [Line Items]
Operating revenues									61,384,000	33,698,000	22,115,000
Depreciation, depletion and amortization									574,000	776,000	1,802,000
Interest expense									(1,316,000)	(1,999,000)	(2,802,000)
Income (loss) before equity in loss from unconsolidated affiliates and income taxes:									25,440,000	4,558,000	(6,772,000)
Payments to Acquire Productive Assets									4,981,000	12,284,000	7,679,000
Assets	129,663,000				141,097,000				129,663,000	141,097,000
Impairment losses										200,000
Commercial real estate
Segment Reporting Information [Line Items]
Operating revenues									3,265,000	10,881,000	10,400,000
Interest expense									(696,000)	(41,000)	(18,000)
Income (loss) before equity in loss from unconsolidated affiliates and income taxes:									(163,000)	3,298,000	(271,000)
Payments to Acquire Productive Assets									854,000	2,388,000	3,829,000
Assets	62,931,000				62,924,000				62,931,000	62,924,000
Resorts, leisure and leasing operations
Segment Reporting Information [Line Items]
Operating revenues									55,451,000	50,767,000	44,407,000
Depreciation, depletion and amortization									6,916,000	6,424,000	5,714,000
Income (loss) before equity in loss from unconsolidated affiliates and income taxes:									1,886,000	(1,928,000)	(1,414,000)
Payments to Acquire Productive Assets									24,798,000	23,486,000	9,023,000
Assets	158,226,000				142,940,000				158,226,000	142,940,000
Impairment losses										4,900,000	2,600,000
Forestry
Segment Reporting Information [Line Items]
Operating revenues									581,442,000	35,450,000	38,977,000
Depreciation, depletion and amortization									729,000	1,775,000	2,105,000
Income (loss) before equity in loss from unconsolidated affiliates and income taxes:									517,087,000	13,406,000	13,475,000
Payments to Acquire Productive Assets									1,537,000	3,678,000	2,701,000
Assets	20,521,000				60,889,000				20,521,000	60,889,000
Corporate
Segment Reporting Information [Line Items]
Investment income, net									11,697,000	1,385,000	639,000
Interest expense									(6,596,000)
Income (loss) before equity in loss from unconsolidated affiliates and income taxes:									(22,429,000)	(14,889,000)	1,405,000
Interest Income, Other									6,100,000
Pension charges									13,500,000	1,500,000	3,000,000
Other
Segment Reporting Information [Line Items]
Operating revenues									331,000	460,000	23,497,000
Depreciation, depletion and amortization									203,000	156,000	489,000
Investment income, net									994,000	113,000	68,000
Payments to Acquire Productive Assets									271,000	224,000	163,000
Assets	$ 931,794,000				$ 261,622,000				$ 931,794,000	$ 261,622,000