Properties, net (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Properties
Projects in development or held for future development	$ 638,919	$ 642,682
Projects in development or held for future development | Land in development or held for future development
Properties
Projects in development or held for future development	229,833	256,487
Projects in development or held for future development | Construction in progress, excluding land
Properties
Projects in development or held for future development	$ 409,086	$ 386,195