FAIR VALUE MEASUREMENTS - Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value Measurement [Domain]
Assets:
Cash and cash equivalents	$ 193,355
Liabilities:
Mortgages payable	1,291,250
Carrying Amount
Assets:
Cash and cash equivalents	193,355	$ 2,600
Liabilities:
Mortgages payable	$ 1,250,031	1,288,535
Fair Value
Assets:
Cash and cash equivalents		2,600
Liabilities:
Mortgages payable		$ 1,327,000