Description of Business and Basis of Presentation (Details Textual) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013 sqft	Dec. 31, 2012
Organization Consolidation And Presentation of Financial Statements
Company's portfolio of real estate assets - Office space (square feet)	14,753,000
Company's portfolio of real estate assets - Retail space (square feet)	566,000
Company's portfolio of real estate assets - apartment space (square feet)	404,000
Total Assets	$ 2,273,206	$ 1,124,242
Callaway [Member]
Organization Consolidation And Presentation of Financial Statements
Total Assets	4,600	4,900
Section 1031 Exchange VIE [Member]
Organization Consolidation And Presentation of Financial Statements
Total Assets	$ 305,800