FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Liabilities:
Allowance, notes receivable	$ 200	$ 500
Nonrecurring | Reported Value Measurement
Assets:
Cash and cash equivalents	450,629	485,424
Notes receivable, net	23,610	28,630
Liabilities:
Fixed-rate debt	1,039,571	1,030,554
Variable-rate debt	1,282,725	962,916
Total mortgages, notes and loans payable	2,322,296	1,993,470
Nonrecurring | Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	450,629	485,424
Notes receivable, net	23,610	28,630
Liabilities:
Fixed-rate debt	1,062,435	1,050,333
Variable-rate debt	1,282,725	962,916
Total mortgages, notes and loans payable	$ 2,345,160	$ 2,013,249