MORTGAGES, NOTES AND LOANS PAYABLE, NET (Borrowing Activity, Footnotes) (Details) - USD ($)					12 Months Ended
	Aug. 18, 2020	Jun. 22, 2020	May 20, 2020	Mar. 26, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Repayment of debt	$ 807,900,000				$ 867,935,000	$ 386,489,000	$ 838,462,000
Loss on extinguishment of debt	13,200,000				13,169,000	$ (4,641,000)	$ 0
The Woodlands Towers at the Waterway and The Woodlands Warehouse | Bridge Loan
Debt Instrument [Line Items]
Aggregate principal amount of debt issued			$ 280,300,000	$ 137,000,000.0
The Woodlands Towers at the Waterway
Debt Instrument [Line Items]
Repayment of debt					63,500,000
The Woodlands Towers at the Waterway | Bridge Loan
Debt Instrument [Line Items]
Repayment of debt				$ 63,500,000
Downtown Summerlin
Debt Instrument [Line Items]
Aggregate principal amount of debt issued		$ 221,500,000
Repayment of debt		$ 33,800,000			255,297,000
110 North Wacker | Variable Interest Entity, Primary Beneficiary
Debt Instrument [Line Items]
Deconsolidation of 110 North Wacker					$ 326,835,000
Senior Notes due 2028 | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount of debt issued	$ 750,000,000
Interest rate (as a percent)	5.375%				5.375%
One-month LIBOR
Debt Instrument [Line Items]
Interest rate margin (as a percent)					0.14%
Three-month LIBOR
Debt Instrument [Line Items]
Interest rate margin (as a percent)					0.24%
Prime rate
Debt Instrument [Line Items]
Interest rate margin (as a percent)					3.25%
LIBOR | The Woodlands Towers at the Waterway and The Woodlands Warehouse | Bridge Loan
Debt Instrument [Line Items]
Interest rate margin (as a percent)			2.35%
LIBOR | Downtown Summerlin
Debt Instrument [Line Items]
Interest rate margin (as a percent)		2.15%