Supplemental Detail for Certain Components of Consolidated Balance Sheets (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts payable and accrued expenses
Bond interest payable	$ 40,061	$ 35,195
Accrued costs on properties under development	8,595	4,766
Other items	21,770	18,809
Total accounts payable and accrued expenses	70,426	58,770
Other liabilities
Value of in-place below-market leases, net	26,471	6,423
Rent received in advance	20,929	18,149
Security deposits	5,130	4,607
Total other liabilities	$ 52,530	$ 29,179