REAL ESTATE AND OTHER AFFILIATES (Summary of Investments in Real Estate and Other Affiliates) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Investment in Real Estate and Other Affiliates
Carrying Value	$ 107,720		$ 107,720		$ 76,593
Share of Earnings/Dividends	8,612	$ 7,467	39,297	$ 25,821
Cost method investments
Investment in Real Estate and Other Affiliates
Carrying Value	3,856		3,856		3,952
Share of Earnings/Dividends	0	0	3,341	3,383
Accounts payable and accrued expenses | The Metropolitan Downtown Columbia
Investment in Real Estate and Other Affiliates
Investment deficit position	$ 3,200		$ 3,200		$ 2,600
MPC | The Summit | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	0.00%		0.00%		0.00%
Carrying Value	$ 76,899		$ 76,899		$ 45,886
Share of Earnings/Dividends	$ 9,454	6,480	$ 34,682	21,552
Operating | Las Vegas 51s LLC | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	100.00%		100.00%		100.00%
Carrying Value	$ 0		$ 0		$ 0
Share of Earnings/Dividends	$ 0	0	$ 0	(152)
Operating | Constellation | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	100.00%		100.00%		100.00%
Carrying Value	$ 0		$ 0		$ 0
Share of Earnings/Dividends	$ 0	107	$ 0	(215)
Operating | The Metropolitan Downtown Columbia | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	50.00%		50.00%		50.00%
Carrying Value	$ 0		$ 0		$ 0
Share of Earnings/Dividends	$ 87	82	$ 371	356
Operating | Stewart Title of Montgomery County, TX | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	50.00%		50.00%		50.00%
Carrying Value	$ 3,740		$ 3,740		$ 3,673
Share of Earnings/Dividends	$ 165	113	$ 393	322
Operating | Woodlands Sarofim 1 | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	20.00%		20.00%		20.00%
Carrying Value	$ 2,732		$ 2,732		$ 2,696
Share of Earnings/Dividends	$ 30	15	$ 66	45
Operating | m.flats/TEN.M | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	50.00%		50.00%		50.00%
Carrying Value	$ 4,168		$ 4,168		$ 6,521
Share of Earnings/Dividends	$ (357)	0	$ (2,661)	0
Operating | 33 Peck Slip | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	35.00%		35.00%		35.00%
Carrying Value	$ 8,734		$ 8,734		$ 0
Share of Earnings/Dividends	(452)	0	(452)	0
Strategic | Equity Method Investments
Investment in Real Estate and Other Affiliates
Carrying Value	103,864		103,864		$ 72,641
Share of Earnings/Dividends	$ 8,612	7,467	$ 35,956	22,438
Strategic | 33 Peck Slip | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	35.00%		35.00%		35.00%
Carrying Value	$ 0		$ 0		$ 8,651
Share of Earnings/Dividends	$ 0	0	$ (240)	(156)
Strategic | Circle T Ranch and Power Center | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	50.00%		50.00%		50.00%
Carrying Value	$ 7,574		$ 7,574		$ 4,455
Share of Earnings/Dividends	$ (318)	650	$ 3,118	650
Strategic | HHMK Development | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	50.00%		50.00%		50.00%
Carrying Value	$ 10		$ 10		$ 10
Share of Earnings/Dividends	$ 0	0	$ 0	0
Strategic | KR Holdings | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	50.00%		50.00%		50.00%
Carrying Value	$ 7		$ 7		$ 749
Share of Earnings/Dividends	$ 3	$ 20	$ 679	$ 36