Notes and Bonds Payable (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Notes and bonds payable	$ 1,293,044	[1]	$ 1,393,537	[1]
Mortgage notes payable [Member] | 5.000%-7.625% Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Mortgage notes	225,242		225,377
Unaccreted discount	(2,755)		(3,728)
Notes and bonds payable	$ 222,487		$ 221,649

[1] Level 3 - Fair value derived from valuation techniques in which one of more significant inputs or significant value drivers are unobservable.