Investments In Unconsolidated Joint Ventures (150 Main Street, L.L.C.) (Narrative) (Details) (USD $)
 3 Months Ended 6 Months Ended
Jul. 15, 2013
Jun. 30, 2013
Oct. 23, 2012
JMP Eastchester, L.L.C. [Member]
Oct. 23, 2012
Hudson Valley Land Holdings, L.L.C. [Member]
Jun. 30, 2013
150 Main Street, L.L.C. [Member]
Jun. 30, 2013
150 Main Street, L.L.C. [Member]
Jun. 30, 2012
150 Main Street, L.L.C. [Member]
Jun. 30, 2013
Eastchester Project [Member]
Oct. 23, 2012
Eastchester Project [Member]
Oct. 23, 2012
Eastchester Project [Member]
150 Main Street, L.L.C. [Member]
item
Jun. 30, 2013
Construction Loan [Member]
Eastchester Project [Member]
150 Main Street, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]                      
Percentage of interest in venture                 26.25%    
Number of units                   108  
Third party ownership percentage     26.25% 47.50%              
Total project costs               $ 46,000,000      
Maximum borrowing capacity 600,000,000 600,000,000                 27,500,000
Amount of project costs funded by members               18,500,000      
Percentage return on unrecovered capital           8.00%          
Development management and other services fees         $ 0 $ 0 $ 15,000        
Holding and distribution pattern under operating agreement           The operating agreement of Eastchester provides, among other things, for the distribution of net operating cash flow to the members, as follows:to HVLH to the extent of its accrued but unpaid preferred return of eight percent on the unrecovered allocated land value, as defined; to the members, pro rata, to the extent of their respective accrued but unpaid return of eight percent on their unrecovered capital percentages; andto the members in accordance with their ownership percentages.