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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Investment in Real Estate and Other Affiliates
Carrying Value	$ 117,821		$ 117,821		$ 102,287
Share of Earnings/Dividends	6,354	$ 16,299	16,305	$ 30,685
Cost method investments
Investment in Real Estate and Other Affiliates
Carrying Value	3,856		3,856		3,856
Share of Earnings/Dividends	0	1	3,625	3,342
Accounts payable and accrued expenses | The Metropolitan Downtown Columbia
Investment in Real Estate and Other Affiliates
Investment deficit position	$ 4,000		$ 4,000		$ 3,800
Operating Assets | 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	$ 123	204	$ 306	284
Operating Assets | 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	$ 3,842		$ 3,842		$ 3,920
Share of Earnings/Dividends	$ 170	145	$ 272	227
Operating Assets | Woodlands Sarofim 1 | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	20.00%		20.00%		20.00%
Carrying Value	$ 2,811		$ 2,811		$ 2,760
Share of Earnings/Dividends	$ 31	16	$ 51	36
Operating Assets | 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	$ 3,236		$ 3,236		$ 4,701
Share of Earnings/Dividends	$ (279)	(1,367)	$ (1,500)	(2,304)
Master Planned Communities | The Summit | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	0.00%		0.00%		0.00%
Carrying Value	$ 83,767		$ 83,767		$ 72,171
Share of Earnings/Dividends	$ 6,499	14,100	$ 14,336	25,228
Seaport District | Mr. C Seaport | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	35.00%		35.00%		35.00%
Carrying Value	$ 8,547		$ 8,547		$ 8,721
Share of Earnings/Dividends	$ (451)	(240)	$ (1,083)	(240)
Seaport District | Bar Wayo (Momofuku) | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	0.00%		0.00%		0.00%
Carrying Value	$ 5,306		$ 5,306		$ 0
Share of Earnings/Dividends	0	0	0	0
Strategic Developments | Equity Method Investments
Investment in Real Estate and Other Affiliates
Carrying Value	113,965		113,965		$ 98,431
Share of Earnings/Dividends	$ 6,354	16,298	$ 12,680	27,343
Strategic Developments | 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	$ 6,281		$ 6,281		$ 5,989
Share of Earnings/Dividends	$ 256	3,436	$ 291	3,436
Strategic Developments | 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 Developments | KR Holdings | Equity Method Investments
Investment in Real Estate and Other Affiliates
Economic/Legal Ownership	50.00%		50.00%		50.00%
Carrying Value	$ 165		$ 165		$ 159
Share of Earnings/Dividends	$ 5	$ 4	$ 7	$ 676