Debt (Details)	12 Months Ended																12 Months Ended		12 Months Ended					0 Months Ended		12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2014 Construction Loans Northstar USD ($)	Dec. 31, 2013 Construction Loans Northstar USD ($)	Dec. 31, 2014 Construction Loans for Working Capital Northstar USD ($)	Dec. 31, 2013 Construction Loans for Working Capital Northstar USD ($)	Dec. 31, 2014 Agribusiness Debt USD ($)	Dec. 31, 2013 Agribusiness Debt USD ($)	Dec. 31, 2014 Swiss Bank Loan Facility Northstar USD ($)	Dec. 31, 2014 Swiss Bank Loan Facility Northstar CHF	Dec. 31, 2014 Mortgages	Dec. 31, 2014 Line of Credit Northstar USD ($)	Dec. 31, 2014 3.7% payments through 2014 Swiss Bank Loan Facility Northstar	Dec. 31, 2013 3.7% payments through 2014 Swiss Bank Loan Facility Northstar USD ($)	Dec. 31, 2014 3.8% payments through 2014 Swiss Bank Loan Facility Northstar	Dec. 31, 2013 3.8% payments through 2014 Swiss Bank Loan Facility Northstar USD ($)	Dec. 31, 2014 3% to 4.75% payments through 2016 Mortgages USD ($)	Dec. 31, 2013 3% to 4.75% payments through 2016 Mortgages USD ($)	Dec. 31, 2014 5% to 5.5% payments through 2016 Mortgages USD ($)	Dec. 31, 2013 5% to 5.5% payments through 2016 Mortgages USD ($)	Dec. 31, 2014 6.5% payments through 2036 Mortgages	Dec. 31, 2013 6.5% payments through 2036 Mortgages USD ($)	Dec. 31, 2014 8.5% payments through 2017 Mortgages USD ($)	Oct. 21, 2014 8.5% payments through 2017 Senior Notes USD ($)	Oct. 21, 2014 8.5% payments through 2017 Senior Notes USD ($)	Dec. 31, 2014 8.5% payments through 2017 Senior Notes Subsidiaries USD ($)	Dec. 31, 2014 10% payments through 2017 Mortgages USD ($)	Dec. 31, 2013 10% payments through 2017 Mortgages USD ($)	Dec. 31, 2014 Real Estate Operations USD ($)	Dec. 31, 2014 Agribusiness Operations USD ($)	Dec. 31, 2014 Agribusiness Operations Line of Credit USD ($)
Line of Credit Facility [Line Items]
Remaining borrowing capacity																													$ 87,300,000	$ 20,700,000
Total mortgage debt	219,496,000	136,767,000															52,379,000	17,307,000	6,918,000	11,491,000		548,000	74,550,000				1,604,000	1,604,000	135,500,000
Weighted average interest rate											6.60%
Maximum borrowing capacity					27,000,000				23,000,000	20,500,000		89,500,000																	134,500,000
Debt Instrument, Face Amount																									75,000,000
Interest rate			5.25%		6.50%		4.99%						3.70%		3.80%						6.50%		8.50%		8.50%		10.00%
Proceeds from debt																								72,500,000
Maximum allowed debt to tangible assets																										45.00%
Maximum secured debt allowed																										75,000,000
Maximum secured debt to tangible assets ratio																										30.00%
Maximum annual acquisition of unimproved real property allowed																										75,000,000
Maximum acquisition of unimproved real property over term of debt allowed																										150,000,000
Minimum tangible assets not subject to debt-secured liens required																										50,000,000
Minimum net worth required																										175,000,000
Minimum cash and equivalents required																										15,000,000
Maximum annual decrease in tangible assets allowed																										25,000,000
Maximum decrease in tangible assets over term of debt allowed																										50,000,000
Amount outstanding			77,567,000	83,533,000	6,350,000	4,750,000	128,000	159,000						14,012,000		3,363,000															84,000,000
Debt to adjusted capitalization ratio required for compliance												0.60
Debt covenant compliance, actual debt to adjusted capitalization ratio, actual												0.60
Debt service coverage ratio												1.25
Minimum debt service coverage ratio required												1.00
Minimum net worth required for compliance												50,000,000
Actual net worth												55,200,000
Debt covenant terms, allowable deposit to prevent default												5,000,000
Deposit potentially required by lender for covenant noncompliance, percentage of unused line of credit												105.00%
Interest rate, minimum																	3.00%		5.00%
Interest rate, maximum																	4.75%		5.50%
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	32,106,000
2016	32,205,000
2017	155,157,000
2018	28,000
2019
Thereafter
Total	219,496,000
Interest costs capitalized related to construction and real estate development costs	3,800,000	2,900,000
Restricted net assets	$ 270,400,000