Description of Business and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2011
Description of Business and Significant Accounting Policies [Abstract]
Description of Business and Significant Accounting Policies	1. Description of Business and Significant Accounting Policies Description of Business The Company is a fully-integrated, self-administered and self-managed equity real estate investment trust (“REIT”) that provides leasing, management, development, construction and other customer-related services for its properties and for third parties. The Company conducts virtually all of its activities through the Operating Partnership. At September 30, 2011, the Company and/or the Operating Partnership wholly owned: 302 in-service office, industrial and retail properties, comprising 29.2 million square feet; 96 rental residential units; 18 for-sale residential condominiums; 601 acres of undeveloped land suitable for future development, of which 523 acres are considered core holdings; and an additional office property that is considered completed but not yet stabilized. The Company is the sole general partner of the Operating Partnership. At September 30, 2011, the Company owned all of the Preferred Units and 72.2 million, or 95.1%, of the Common Units. Limited partners (including one officer and two directors of the Company) own the remaining 3.8 million Common Units. Generally, the Operating Partnership is obligated to redeem each Common Unit at the request of the holder thereof for cash equal to the value of one share of Common Stock, $.01 par value, based on the average of the market price for the 10 trading days immediately preceding the notice date of such redemption provided that the Company, at its option, may elect to acquire any such Common Units presented for redemption for cash or one share of Common Stock. The Common Units owned by the Company are not redeemable. During the nine months ended September 30, 2011, the Company redeemed 43,308 Common Units for a like number of shares of Common Stock. Common Stock Offering We have entered into equity sales agreements with various financial institutions to offer and sell, from time to time, shares of our Common Stock by means of ordinary brokers’ transactions on the New York Stock Exchange or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices or as otherwise agreed with any of the institutions. During the third quarter of 2011, we issued 142,000 shares of Common Stock under these agreements at an average price of $34.21 per share raising net proceeds, after sales commissions and expenses, of $4.8 million. Basis of Presentation Our Consolidated Financial Statements are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Our Consolidated Statements of Income for the three and nine months ended September 30, 2010 were revised from previously reported amounts to reflect those properties sold or held for sale which required discontinued operations presentation. Our Consolidated Financial Statements include the Operating Partnership, wholly owned subsidiaries and those entities in which we have the controlling financial interest. All significant intercompany transactions and accounts have been eliminated. At September 30, 2011 and December 31, 2010, we were not involved with any entities that were determined to be variable interest entities. The unaudited interim consolidated financial statements and accompanying unaudited consolidated financial information, in the opinion of management, contain all adjustments (including normal recurring accruals) necessary for a fair presentation of our financial position, results of operations and cash flows. We have omitted certain notes and other information from the interim consolidated financial statements presented in this Quarterly Report on Form 10-Q as permitted by SEC rules and regulations. These Consolidated Financial Statements should be read in conjunction with our 2010 Annual Report on Form 10-K. Use of Estimates The preparation of consolidated financial statements in accordance with GAAP requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Recently Issued Accounting Standards Beginning with our Quarterly Report on Form 10-Q for the three months ended March 31, 2012, we will be required to enhance our disclosure of assets and liabilities measured at fair value. This includes disclosing any significant transfers between Levels 1 and 2 of the fair value hierarchy, additional quantitative and qualitative information regarding fair value measurements categorized as Level 3 of the fair value hierarchy and the hierarchy classification for items whose fair value is not recorded on our Consolidated Balance Sheets but is disclosed in our Notes to Consolidated Financial Statements. Additionally, we will be required to present comprehensive income on the face of our Consolidated Statements of Income, which previously has been disclosed in our Notes to Consolidated Financial Statements.

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.