INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Details) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended				1 Months Ended									1 Months Ended						1 Months Ended		1 Months Ended				1 Months Ended				1 Months Ended					1 Months Ended		1 Months Ended					1 Months Ended									12 Months Ended							1 Months Ended	12 Months Ended																																					1 Months Ended							3 Months Ended	12 Months Ended				1 Months Ended							3 Months Ended	12 Months Ended			12 Months Ended			12 Months Ended				12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010	Oct. 31, 2009 Hamilton Park Towers, LLC	Dec. 31, 2012 Hamilton Park Towers, LLC item	Dec. 31, 2011 Hamilton Park Towers, LLC item	Dec. 31, 2010 Hamilton Park Towers, LLC item	Oct. 28, 2009 Hamilton Park Towers, LLC item	Oct. 31, 2009 Hamilton Park Towers, LLC Mortgage loan	Dec. 31, 2012 Hamilton Park Towers, LLC Mortgage loan	Oct. 28, 2009 Hamilton Park Towers, LLC Mortgage loan	Feb. 03, 2013 Hamilton Bay Apartments, LLC item	Dec. 31, 2012 Hamilton Bay Apartments, LLC item	Dec. 31, 2011 Hamilton Bay Apartments, LLC item	Dec. 31, 2010 Hamilton Bay Apartments, LLC item	Apr. 30, 2008 Hamilton Bay Apartments, LLC item	Oct. 03, 2005 Hamilton Bay Apartments, LLC item	Apr. 30, 2008 Hamilton Bay Apartments, LLC Mortgage loan	Feb. 01, 2013 Hamilton Bay Apartments, LLC Mortgage loan item	Dec. 31, 2012 Hamilton Bay, LLC item	Dec. 31, 2011 Hamilton Bay, LLC item	Dec. 31, 2010 Hamilton Bay, LLC item	Oct. 03, 2005 Hamilton Bay, LLC item	Feb. 28, 2007 Hamilton Bay, LLC Mortgage loan	Mar. 07, 2005 Hamilton Essex Development, LLC and Hamilton Essex 81, LLC	Mar. 31, 2005 Hamilton Essex Development, LLC and Hamilton Essex 81, LLC Mortgage loan	Dec. 31, 2012 Hamilton Essex 81, LLC item	Dec. 31, 2011 Hamilton Essex 81, LLC item	Dec. 31, 2010 Hamilton Essex 81, LLC item	Aug. 31, 2008 Hamilton Essex 81, LLC Mortgage loan	Dec. 31, 2012 Hamilton Essex Development, LLC item	Dec. 31, 2011 Hamilton Essex Development, LLC item	Dec. 31, 2010 Hamilton Essex Development, LLC item	Aug. 31, 2008 Hamilton Essex Development, LLC Mortgage loan	Dec. 31, 2012 Hamilton 1025, LLC item	Dec. 31, 2011 Hamilton 1025, LLC item	Dec. 31, 2010 Hamilton 1025, LLC item	Mar. 02, 2005 Hamilton 1025, LLC item	Mar. 31, 2005 Hamilton 1025, LLC Mortgage loan	Mar. 02, 2005 Hamilton 1025, LLC Mortgage loan	Oct. 31, 2004 Hamilton Minuteman, LLC	Dec. 31, 2012 Hamilton Minuteman, LLC item	Dec. 31, 2011 Hamilton Minuteman, LLC item	Dec. 31, 2010 Hamilton Minuteman, LLC item	Sep. 30, 2004 Hamilton Minuteman, LLC item	Jan. 31, 2007 Hamilton Minuteman, LLC Mortgage loan	Oct. 31, 2004 Hamilton Minuteman, LLC Mortgage loan	Dec. 31, 2012 Hamilton Minuteman, LLC Mortgage loan	Dec. 31, 2006 Hamilton Minuteman, LLC Mortgage loan	Dec. 31, 2012 Hamilton on Main, LLC item	Dec. 31, 2011 Hamilton on Main, LLC item	Dec. 31, 2010 Hamilton on Main, LLC item	May 31, 2008 Hamilton on Main, LLC item	Aug. 31, 2004 Hamilton on Main, LLC item	Dec. 31, 2012 Hamilton on Main Apartments, LLC	Dec. 31, 2005 Hamilton on Main Apartments, LLC Mortgage loan	Dec. 31, 2012 Hamilton on Main Apartments, LLC Mortgage loan	Dec. 31, 2012 345 Franklin, LLC item	Dec. 31, 2011 345 Franklin, LLC item	Dec. 31, 2010 345 Franklin, LLC item	Nov. 30, 2001 345 Franklin, LLC item	Nov. 30, 2001 345 Franklin, LLC Mortgage loan	Dec. 31, 2012 345 Franklin, LLC Mortgage loan	Dec. 31, 2012 Residential buildings Hamilton Park Towers, LLC item	Dec. 31, 2011 Residential buildings Hamilton Park Towers, LLC item	Dec. 31, 2010 Residential buildings Hamilton Park Towers, LLC item	Dec. 31, 2012 Residential buildings Hamilton Bay Apartments, LLC item	Dec. 31, 2011 Residential buildings Hamilton Bay Apartments, LLC item	Dec. 31, 2010 Residential buildings Hamilton Bay Apartments, LLC item	Dec. 31, 2012 Residential buildings Hamilton Bay, LLC item	Dec. 31, 2011 Residential buildings Hamilton Bay, LLC item	Dec. 31, 2010 Residential buildings Hamilton Bay, LLC item	Dec. 31, 2012 Residential buildings Hamilton Essex 81, LLC item	Dec. 31, 2011 Residential buildings Hamilton Essex 81, LLC item	Dec. 31, 2010 Residential buildings Hamilton Essex 81, LLC item	Dec. 31, 2012 Residential buildings Hamilton 1025, LLC item	Dec. 31, 2011 Residential buildings Hamilton 1025, LLC item	Dec. 31, 2010 Residential buildings Hamilton 1025, LLC item	Dec. 31, 2012 Residential buildings Hamilton Minuteman, LLC item	Dec. 31, 2011 Residential buildings Hamilton Minuteman, LLC item	Dec. 31, 2010 Residential buildings Hamilton Minuteman, LLC item	Dec. 31, 2012 Residential buildings Hamilton on Main, LLC item	Dec. 31, 2011 Residential buildings Hamilton on Main, LLC item	Dec. 31, 2010 Residential buildings Hamilton on Main, LLC item	Dec. 31, 2012 Residential buildings 345 Franklin, LLC item	Dec. 31, 2011 Residential buildings 345 Franklin, LLC item	Dec. 31, 2010 Residential buildings 345 Franklin, LLC item	Mar. 07, 2005 Apartment Hamilton Essex Development, LLC and Hamilton Essex 81, LLC item	Mar. 07, 2005 Commercial Hamilton Essex Development, LLC and Hamilton Essex 81, LLC item	Dec. 31, 2012 Commercial Hamilton Essex 81, LLC item	Dec. 31, 2011 Commercial Hamilton Essex 81, LLC item	Dec. 31, 2010 Commercial Hamilton Essex 81, LLC item	Dec. 31, 2012 Commercial Hamilton Essex Development, LLC item	Dec. 31, 2011 Commercial Hamilton Essex Development, LLC item	Dec. 31, 2010 Commercial Hamilton Essex Development, LLC item	Dec. 31, 2012 Commercial Hamilton 1025, LLC item	Dec. 31, 2011 Commercial Hamilton 1025, LLC item	Dec. 31, 2010 Commercial Hamilton 1025, LLC item	Mar. 07, 2005 Car parking lot Hamilton Essex Development, LLC and Hamilton Essex 81, LLC item	Apr. 30, 2012 HBC	Feb. 29, 2012 HBC	Dec. 31, 2011 HBC	Oct. 31, 2011 HBC	Aug. 31, 2011 HBC	Aug. 31, 2010 HBC	Oct. 31, 2009 HBC	Dec. 31, 2010 HBC	Dec. 31, 2012 HBC	Dec. 31, 2011 HBC	Dec. 31, 2010 HBC	Oct. 28, 2009 HBC	Apr. 30, 2012 HBC Hamilton Park Towers, LLC Mortgage loan	Feb. 29, 2012 HBC Hamilton Park Towers, LLC Mortgage loan	Dec. 31, 2011 HBC Hamilton Park Towers, LLC Mortgage loan	Oct. 31, 2011 HBC Hamilton Park Towers, LLC Mortgage loan	Aug. 31, 2011 HBC Hamilton Park Towers, LLC Mortgage loan	Aug. 31, 2010 HBC Hamilton Park Towers, LLC Mortgage loan	Oct. 31, 2009 HBC Hamilton Park Towers, LLC Mortgage loan	Dec. 31, 2010 HBC Hamilton Park Towers, LLC Mortgage loan	Dec. 31, 2012 HBC Hamilton Park Towers, LLC Mortgage loan	Dec. 31, 2011 HBC Hamilton Park Towers, LLC Mortgage loan	Oct. 28, 2009 HBC Hamilton Park Towers, LLC Mortgage loan	Dec. 31, 2012 Management Company item	Dec. 31, 2012 Minimum Mortgage loan	Dec. 31, 2012 Minimum Limited Partnerships	Dec. 31, 2012 Minimum Hamilton on Main Apartments, LLC	Dec. 31, 2012 Minimum Harold Brown	Dec. 31, 2012 Maximum Mortgage loan	Dec. 31, 2012 Maximum Limited Partnerships	Dec. 31, 2012 Maximum Hamilton on Main Apartments, LLC	Dec. 31, 2012 Maximum Harold Brown
INVESTMENT IN UNCONSOLIDATED JOINT VENTURES
Number of limited partnerships and limited liability companies in which the entity has invested	9
Number of partnerships investing in commercial property	3
Percentage of ownership interest								40.00%									50.00%								50.00%													50.00%							50.00%									50.00%							50.00%																																																																40.00%		43.20%		50.00%		60.00%
Number of employees having ownership interest																																																																																																																											6
Investments in joint venture	$ 13,986,173	$ 16,780,657						$ 15,925,000									$ 2,500,000								$ 2,000,000													$ 2,352,000							$ 5,075,000									$ 8,000,000							$ 1,533,000
Number of units					409	409	409	409					48	48	48	20	168			120	120	120					49	49	49		1	1	1		176	176	176	176				42	42	42	42					148	148	148		280				40	40	40	40			409	409	409	48	48	48	120	120	120	48	48	48	175	175	175	42	42	42	148	148	148	40	40	40	49		1	1	1	1	1	1	1	1	1
Number of properties																																																																																									1
Purchase price of investments								129,500,000									30,875,000								14,300,000													23,750,000							10,100,000									56,000,000
Borrowings									89,914,000									2,368,000						4,750,000		10,750,000				8,352,000				2,093,000					5,000,000							5,500,000	8,025,000									16,825,000																																																		7,168,000												7,168,000		7,168,000
Interest rate (as a percent)											5.57%							5.75%						5.57%						5.79%										5.67%						5.67%										5.18%						6.90%																																																	6.00%											6.00%
Interest rate (as a percent)																																																																																																																												2.80%				6.90%
Period for which the entity is required to make interest only payments									2 years															5 years															5 years							5 years										3 years
Amortization period of debt									30 years															30 years						30 years									30 years							30 years										30 years						30 years
Outstanding amount of mortgage loan	138,055,522	139,161,612			88,611,686	89,733,192	89,914,000			88,612,000			4,702,087	4,750,000	4,750,000					1,668,000	1,668,000	1,668,000					8,352,317	8,462,041	8,566,871		2,093,184	2,144,796	2,162,000		4,934,741	4,995,487	5,000,000					5,433,472	5,500,000	5,500,000				5,433,000		15,611,045	15,887,203	16,151,526					15,611,000	6,850,179	7,019,119	7,176,827																																										1,668,600							1,668,600					1,668,600							1,668,600
Investments funded using cash reserves				8,757,000
Term of debt																																							10 years							10 years										10 years						12 years																																												4 years												4 years
Notice period for principal paydown of debt																																																																																																										6 months												6 months
Principal amount requested to be repaid																																																																																																									2,500,000												2,500,000
Repayment of loan																																																																																																				918,600							2,500,000					918,600							2,500,000
Principal payments elected to be made																																																																																																					750,000	1,000,000	1,000,000	1,000,000									750,000	1,000,000	1,000,000	1,000,000
Interest paid	7,776,000	8,011,000	8,182,000																																																																																																									18,960	238,673	414,740										18,960	238,673
Amortization period of intangible assets					12 months
Number of units retained for long-term investment					409	409	409						48	48	48								48				49	49	49		1	1	1		49	49	49	49				42	42	42						148	148	148						40	40	40
Number of units sold												105							105	105	105	105													127	127	127	127															137
Capacity of real estate property (in cars per lot)																																																																																																			50
Margin over basis of interest rate (as a percent)																																		2.25%
Basis of interest rate																																		Libor
Notional margin over basis of interest rate (as a percent)																																		0.21%
Principal amount of debt to be paid per month																																		4,301
Cost associated with loan extension																																		6,000
Amount returned to partnership																																									3,775,000
Cash contribution by the entity towards loan																																																	1,250,000
Ownership percentage in third party entity by majority shareholder of the General Partner																																																							31.00%
Ownership percentage in third party entity by President of management company																																																							5.00%
Percentage of variable commission on each sale																																																																																																																														3.00%				5.00%
Term excluding period for which interest only payments to be made																																																								7 years
Net proceeds after funding escrow accounts and closing costs																																																								16,700,000
Fee for early extinguishment of debt																																																								400,000
Final payment due on the maturity date																																																															$ 6,000,000