FAIR VALUES OF FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets:
Secured loans receivable, net	$ 490,107	$ 635,002
Unsecured loans receivable, net	65,009	62,118
Liabilities:
Redeemable OP unitholder interests	129,800	114,900
Carrying Amount
Assets:
Cash and cash equivalents	57,690	67,908
Secured loans receivable, net	490,107	635,002
Unsecured loans receivable, net	65,009	62,118
Liabilities:
Senior notes payable and other debt, gross	8,229,589	8,186,315
Derivative instruments and other liabilities	25,380	45,966
Redeemable OP unitholder interests	129,773	114,933
Fair Value
Assets:
Cash and cash equivalents	57,690	67,908
Secured loans receivable, net	487,814	636,714
Unsecured loans receivable, net	67,767	65,146
Liabilities:
Senior notes payable and other debt, gross	8,578,726	8,600,450
Derivative instruments and other liabilities	25,380	45,966
Redeemable OP unitholder interests	$ 129,773	$ 114,933