REAL ESTATE AND OTHER AFFILIATES (Summary of Investments in Real Estate and Other Affiliates) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Investment in Real Estate and Other Affiliates
Carrying Value	$ 99,444		$ 99,444		$ 76,593
Share of Earnings/Dividends	16,299	$ 9,834	30,685	$ 18,354
Cost method investments
Investment in Real Estate and Other Affiliates
Carrying Value	3,856		3,856		3,952
Share of Earnings/Dividends	1	0	3,342	3,383
Accounts payable and accrued expenses | The Metropolitan Downtown Columbia
Investment in Real Estate and Other Affiliates
Investment deficit position	$ 3,100		$ 3,100		$ 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	$ 68,370		$ 68,370		$ 45,886
Share of Earnings/Dividends	$ 14,100	9,792	$ 25,228	15,072
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	(385)	$ 0	(322)
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	$ 204	216	$ 284	274
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	$ 3,676		$ 3,676		$ 3,673
Share of Earnings/Dividends	$ 145	183	$ 227	209
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	$ 2,702		$ 2,702		$ 2,696
Share of Earnings/Dividends	$ 16	23	$ 36	30
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	$ 4,281		$ 4,281		$ 6,521
Share of Earnings/Dividends	(1,367)	0	(2,304)	0
Strategic | Equity Method Investments
Investment in Real Estate and Other Affiliates
Carrying Value	95,588		95,588		$ 72,641
Share of Earnings/Dividends	$ 16,298	9,834	$ 27,343	14,971
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	$ 7,891		$ 7,891		$ 4,455
Share of Earnings/Dividends	$ 3,436	0	$ 3,436	0
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	$ 4		$ 4		$ 749
Share of Earnings/Dividends	$ 4	5	$ 676	16
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	$ 8,654		$ 8,654		$ 8,651
Share of Earnings/Dividends	$ (240)	$ 0	$ (240)	$ (156)