FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Liabilities:
Allowance, notes receivable	$ 300	$ 500
Nonrecurring | Reported Value Measurement
Assets:
Cash and cash equivalents	488,611	485,424
Notes receivable, net	25,138	28,630
Liabilities:
Fixed-rate debt	1,047,606	1,030,554
Variable-rate debt	1,238,568	962,916
Total mortgages, notes and loans payable	2,286,174	1,993,470
Nonrecurring | Estimate of Fair Value Measurement
Assets:
Cash and cash equivalents	488,611	485,424
Notes receivable, net	25,138	28,630
Liabilities:
Fixed-rate debt	1,102,460	1,050,333
Variable-rate debt	1,238,568	962,916
Total mortgages, notes and loans payable	$ 2,341,028	$ 2,013,249