Description of Business and Basis of Presentation (Details Textual) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011 sqft Property acre	Dec. 31, 2010	Dec. 31, 2009
Description of Business and Basis of Presentation (Textual) [Abstract]
Total Assets	$ 1,235,535	$ 1,371,282	$ 1,491,552
Total Liabilities	595,377	564,142
Description of Business and Basis of Presentation Additional (Textual) [Abstract]
Company's portfolio of real estate assets - Office space	7,800,000
Company's portfolio of real estate assets - Retail space	4,800,000
Interests in residential communities under development or held for future development	22
Strategically located land tracts held for investment or future development and significant land holdings for development of single-family residential communities	5,000
Office and retail space owned by third parties which the Company also provides leasing and/or management services	12,700,000
Callaway [Member]
Description of Business and Basis of Presentation (Textual) [Abstract]
Total Assets	4,900	15,700
Total Liabilities	$ 0	$ 0