Segment Information - Information by Business Segment (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) Segment golf_course	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable operating segments | Segment									5
Operating revenue	$ 18,747,000	$ 27,192,000	$ 29,551,000	$ 20,254,000	$ 21,104,000	$ 27,830,000	$ 37,846,000	$ 17,091,000	$ 95,744,000	$ 103,871,000	$ 701,873,000
Cost of Revenue									8,036,000	16,399,000	87,132,000
Other operating and corporate expenses									23,019,000	33,426,000	26,128,000
Depreciation, depletion and amortization									8,571,000	9,486,000	8,422,000
Investment income, net									17,776,000	22,688,000	12,691,000
Interest expense									(12,295,000)	(11,429,000)	(8,608,000)
Income (Loss) Before Equity In Loss From Unconsolidated Affiliates and Income Taxes									22,611,000	(1,163,000)	521,821,000
Capital expenditures									12,858,000	17,465,000	32,441,000
Assets	1,027,945,000				982,742,000				1,027,945,000	982,742,000
Interest Income, Other									348,000	694,000	990,000
Pension charges									0	0	13,529,000
Residential real estate
Segment Reporting Information [Line Items]
Operating revenue									19,483,000	21,137,000	61,444,000
Cost of Revenue									6,383,000	10,853,000	27,562,000
Other operating and corporate expenses									5,744,000	10,215,000	8,269,000
Depreciation, depletion and amortization									286,000	544,000	662,000
Interest expense									(1,284,000)	(1,174,000)	(1,316,000)
Income (Loss) Before Equity In Loss From Unconsolidated Affiliates and Income Taxes									5,887,000	(821,000)	24,854,000
Capital expenditures									3,319,000	4,923,000	4,981,000
Assets	112,220,000				109,791,000				112,220,000	109,791,000
Commercial real estate
Segment Reporting Information [Line Items]
Operating revenue									2,187,000	7,160,000	3,265,000
Cost of Revenue									1,323,000	4,974,000	1,031,000
Other operating and corporate expenses									2,167,000	2,104,000	2,271,000
Interest expense									(2,169,000)	(1,489,000)	(696,000)
Income (Loss) Before Equity In Loss From Unconsolidated Affiliates and Income Taxes									(1,323,000)	126,000	(163,000)
Capital expenditures									3,937,000	2,165,000	854,000
Assets	62,009,000				62,649,000				62,009,000	62,649,000
Resorts and leisure
Segment Reporting Information [Line Items]
Operating revenue									57,284,000	54,488,000	48,414,000
Cost of Revenue									50,229,000	47,069,000	42,900,000
Other operating and corporate expenses									547,000	426,000	452,000
Depreciation, depletion and amortization									4,402,000	5,096,000	4,143,000
Income (Loss) Before Equity In Loss From Unconsolidated Affiliates and Income Taxes									2,087,000	1,819,000	1,559,000
Capital expenditures									1,287,000	2,526,000	2,198,000
Assets	73,436,000				75,441,000				$ 73,436,000	75,441,000
Number of golf courses | golf_course									4
Leasing operations
Segment Reporting Information [Line Items]
Operating revenue									$ 9,742,000	8,978,000	6,977,000
Cost of Revenue									3,108,000	2,792,000	2,253,000
Other operating and corporate expenses									1,325,000	927,000	557,000
Depreciation, depletion and amortization									3,137,000	3,118,000	2,685,000
Income (Loss) Before Equity In Loss From Unconsolidated Affiliates and Income Taxes									90,000	676,000	1,165,000
Capital expenditures									2,899,000	5,849,000	22,600,000
Assets	79,004,000				81,400,000				79,004,000	81,400,000
Forestry revenue
Segment Reporting Information [Line Items]
Operating revenue									6,673,000	12,042,000	581,442,000
Cost of Revenue									1,121,000	1,402,000	63,029,000
Other operating and corporate expenses									530,000	941,000	1,910,000
Depreciation, depletion and amortization									552,000	581,000	729,000
Income (Loss) Before Equity In Loss From Unconsolidated Affiliates and Income Taxes									5,609,000	10,259,000	517,087,000
Capital expenditures									1,095,000	1,366,000	1,537,000
Assets	20,664,000				20,244,000				20,664,000	20,244,000
Residential real estate and other
Segment Reporting Information [Line Items]
Investment income, net									97,000	571,000	994,000
Corporate
Segment Reporting Information [Line Items]
Investment income, net									17,679,000	22,117,000	11,697,000
Interest expense									(8,842,000)	(8,766,000)	(6,596,000)
Income (Loss) Before Equity In Loss From Unconsolidated Affiliates and Income Taxes									10,261,000	(13,222,000)	(22,681,000)
Interest Income, Other									8,200,000	8,200,000	6,100,000
Other
Segment Reporting Information [Line Items]
Operating revenue									375,000	66,000	331,000
Cost of Revenue									30,000	4,000	23,000
Other operating and corporate expenses									12,706,000	18,813,000	12,669,000
Depreciation, depletion and amortization									194,000	147,000	203,000
Capital expenditures									321,000	636,000	271,000
Assets	$ 680,612,000				$ 633,217,000				680,612,000	633,217,000
Operating Segments
Segment Reporting Information [Line Items]
Operating revenue									95,744,000	103,871,000	701,873,000
Cost of Revenue									62,194,000	67,094,000	136,798,000
Other operating and corporate expenses									$ 23,019,000	$ 33,426,000	26,128,000
RiverTown Sale
Segment Reporting Information [Line Items]
Operating revenue											43,600,000
Cost of Revenue											17,600,000
AgReserves Sale
Segment Reporting Information [Line Items]
Operating revenue											570,900,000
Cost of Revenue											$ 58,400,000