Subsequent Events (Notes)	3 Months Ended
Mar. 31, 2016
Subsequent Events [Abstract]
Subsequent Events [Text Block]	SUBSEQUENT EVENTS On April 28, 2016, the Company and Parkway Properties, Inc. (“Parkway”) entered into an Agreement and Plan of Merger (the “Merger Agreement”), pursuant to which Parkway will merge with and into the Company (the “Merger”). In addition, the Merger Agreement provides that the Company will separate the portion of the combined businesses relating to the ownership of real properties in Houston (the “Houston Business”) from the remainder of the combined business by distributing pro rata to its stockholders all of the outstanding shares of common stock of an entity (“HoustonCo”) containing the Houston Business (the “Spin-Off”). The Company will retain all of the shares of a class of non-voting preferred stock of HoustonCo, upon the terms and subject to the conditions of the Merger Agreement. The Company expects that the Spin-Off will be treated for tax purposes as a distribution to the Company’s stockholders equal to the fair market value of the distributed HoustonCo shares. After the Spin-Off, HoustonCo will be a separate, publicly-traded entity, and both the Company and HoustonCo intend to operate prospectively as umbrella real estate investment trusts (“UPREITs”). Pursuant to the Merger Agreement, upon closing, each share of Parkway common stock issued and outstanding converted into the right to receive 1.63 (the “Exchange Ratio”) shares of newly issued shares of common stock, par value $1 per share, of the Company. In addition, each share of Parkway limited voting stock, par value issued will be converted into the right to receive a number of newly issued shares of limited voting preferred stock of the Company, equal to the Exchange Ratio, having terms materially unchanged from the terms of the Parkway limited voting stock prior to the Merger. Each share of Parkway equity-based compensation awards will also be converted at the Exchange Ratio into equity awards of the Company. Limited partnership units of Parkway LP, Parkway’s umbrella partnership, will be entitled to redeem or exchange their partnership interest for the Company’s common stock at the Exchange Ratio. The respective boards of directors (the “Board of Directors”) of the Company and Parkway have unanimously approved the Merger Agreement and have recommended that their respective stockholders approve the Merger. The closing of the Merger is subject to certain conditions, including: (1) the receipt of Parkway Stockholder Approval; (2) the receipt of Company Stockholder Approvals; (3) the Spin-Off being fully ready to be consummated contemporaneously with the Merger; (4) approval for listing on the New York Stock Exchange (“NYSE”) of the Company common stock to be issued in the Merger or reserved for issuance in connection therewith; (5) no injunction or law prohibiting the Merger; (6) accuracy of each party’s representations, subject in most cases to materiality or material adverse effect qualifications; (7) material compliance with each party’s covenants; (8) receipt by each of the Company and Parkway of an opinion to the effect that the Merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended (the “Code”), and of an opinion that each of the Company and Parkway will qualify as a real estate investment trust (“REIT”) under the Code; and (9) effectiveness of the registration statement that will contain the joint proxy statement/prospectus sent to Company and Parkway stockholders. The Merger Agreement contains customary representations and warranties by each party. The Company and Parkway have also agreed to various customary covenants and agreements, including, among others, to conduct their business in the ordinary course consistent with past practice during the period between the execution of the Merger Agreement and the Effective Time, to not engage in certain kinds of transactions during this period and to maintain REIT status. The parties are subject to a customary “no-shop” provision that requires them to cease discussions or solicitations with respect to alternate transactions and subjects them to certain restrictions in considering and negotiating alternate transactions. Additionally, Parkway has agreed to use commercially reasonable efforts to sell certain of its properties prior to the closing date, upon the terms and subject to the conditions of the Merger Agreement. The Company and Parkway have also agreed that, prior to the closing, each may continue to pay their regular quarterly dividends, but may not increase the amounts, except to the extent required to maintain REIT status. The parties will coordinate record and payment dates for all pre-closing dividends. The Merger Agreement provides that the Board of Directors of the Company will consist of nine members, including five individuals to be selected by the current members of the Board of Directors of the Company and four individuals to be selected by the current members of the Board of Directors of Parkway. One of Parkway’s four directors will be selected by TPG Pantera VI (“TPG”) and TPG Management (collectively with TPG, the “TPG Parties”), pursuant to the TPG Parties’ stockholders agreement to be entered into with the Company. The Merger Agreement contains certain termination rights for the Company and Parkway. The Merger Agreement can be terminated by either party (1) by mutual written consent; (2) if the Merger has not been consummated by an outside date of December 31, 2016 (which either party may extend to March 31, 2017 if the only closing condition that has not been met is that related to the readiness of the Spin-Off ); (3) if there is a permanent, non-appealable injunction or law restraining or prohibiting the consummation of the Merger; (4) if either party’s stockholders fail to approve the transactions; (5) if the other party’s Board of Directors changes its recommendation in favor of the transactions; (6) if the other party has materially breached its non-solicit covenant, subject to a cure period; (7) in order to enter into a superior proposal (as defined in the Merger Agreement, subject to compliance with certain terms and conditions included in the Merger Agreement); or (8) if the other party has breached its representations or covenants in a way that prevents satisfaction of a closing condition, subject to a cure period. If the Merger Agreement is terminated because (1) a party’s Board of Directors changes its recommendation in favor of the transactions contemplated by the Merger Agreement; (2) a party terminates the agreement to enter into a superior proposal; (3) a party breaches its non-solicit covenant; or (4) a party consummates or enters into an agreement for an alternative transaction within twelve months following termination under certain circumstances, such party must pay a termination fee of the lesser of $65 million or the maximum amount that could be paid to the other party without causing it to fail to meet the REIT requirements for such year. The Merger Agreement also provides that a party must pay the other party an expense reimbursement of the lesser of $20 million and the maximum amount that can be paid to the other party without causing it to fail to meet the REIT requirements for such year, if the Merger Agreement is terminated because such party’s stockholders vote against the transactions contemplated by the Merger Agreement. Any unpaid amount of the foregoing fees (due to limitations of REIT requirements) will be escrowed and paid out over a five-year period. The expense reimbursement will be set off against the termination fee if the termination fee later becomes payable. The Merger and Spin-Off are currently anticipated to close in the fourth quarter of 2016.

SUBSEQUENT EVENTS

On April 28, 2016, the Company and Parkway Properties, Inc. (“Parkway”) entered into an Agreement and Plan of Merger (the “Merger Agreement”), pursuant to which Parkway will merge with and into the Company (the “Merger”). In addition, the Merger Agreement provides that the Company will separate the portion of the combined businesses relating to the ownership of real properties in Houston (the “Houston Business”) from the remainder of the combined business by distributing pro rata to its stockholders all of the outstanding shares of common stock of an entity (“HoustonCo”) containing the Houston Business (the “Spin-Off”). The Company will retain all of the shares of a class of non-voting preferred stock of HoustonCo, upon the terms and subject to the conditions of the Merger Agreement. The Company expects that the Spin-Off will be treated for tax purposes as a distribution to the Company’s stockholders equal to the fair market value of the distributed HoustonCo shares. After the Spin-Off, HoustonCo will be a separate, publicly-traded entity, and both the Company and HoustonCo intend to operate prospectively as umbrella real estate investment trusts (“UPREITs”).

Pursuant to the Merger Agreement, upon closing, each share of Parkway common stock issued and outstanding converted into the right to receive 1.63 (the “Exchange Ratio”) shares of newly issued shares of common stock, par value $1 per share, of the Company. In addition, each share of Parkway limited voting stock, par value issued will be converted into the right to receive a number of newly issued shares of limited voting preferred stock of the Company, equal to the Exchange Ratio, having terms materially unchanged from the terms of the Parkway limited voting stock prior to the Merger. Each share of Parkway equity-based compensation awards will also be converted at the Exchange Ratio into equity awards of the Company. Limited partnership units of Parkway LP, Parkway’s umbrella partnership, will be entitled to redeem or exchange their partnership interest for the Company’s common stock at the Exchange Ratio.

The respective boards of directors (the “Board of Directors”) of the Company and Parkway have unanimously approved the Merger Agreement and have recommended that their respective stockholders approve the Merger.

The closing of the Merger is subject to certain conditions, including: (1) the receipt of Parkway Stockholder Approval; (2) the receipt of Company Stockholder Approvals; (3) the Spin-Off being fully ready to be consummated contemporaneously with the Merger; (4) approval for listing on the New York Stock Exchange (“NYSE”) of the Company common stock to be issued in the Merger or reserved for issuance in connection therewith; (5) no injunction or law prohibiting the Merger; (6) accuracy of each party’s representations, subject in most cases to materiality or material adverse effect qualifications; (7) material compliance with each party’s covenants; (8) receipt by each of the Company and Parkway of an opinion to the effect that the Merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended (the “Code”), and of an opinion that each of the Company and Parkway will qualify as a real estate investment trust (“REIT”) under the Code; and (9) effectiveness of the registration statement that will contain the joint proxy statement/prospectus sent to Company and Parkway stockholders.

The Merger Agreement contains customary representations and warranties by each party. The Company and Parkway have also agreed to various customary covenants and agreements, including, among others, to conduct their business in the ordinary course consistent with past practice during the period between the execution of the Merger Agreement and the Effective Time, to not engage in certain kinds of transactions during this period and to maintain REIT status. The parties are subject to a customary “no-shop” provision that requires them to cease discussions or solicitations with respect to alternate transactions and subjects them to certain restrictions in considering and negotiating alternate transactions.

Additionally, Parkway has agreed to use commercially reasonable efforts to sell certain of its properties prior to the closing date, upon the terms and subject to the conditions of the Merger Agreement. The Company and Parkway have also agreed that, prior to the closing, each may continue to pay their regular quarterly dividends, but may not increase the amounts, except to the extent required to maintain REIT status. The parties will coordinate record and payment dates for all pre-closing dividends.

The Merger Agreement provides that the Board of Directors of the Company will consist of nine members, including five individuals to be selected by the current members of the Board of Directors of the Company and four individuals to be selected by the current members of the Board of Directors of Parkway. One of Parkway’s four directors will be selected by TPG Pantera VI (“TPG”) and TPG Management (collectively with TPG, the “TPG Parties”), pursuant to the TPG Parties’ stockholders agreement to be entered into with the Company.

The Merger Agreement contains certain termination rights for the Company and Parkway. The Merger Agreement can be terminated by either party (1) by mutual written consent; (2) if the Merger has not been consummated by an outside date of December 31, 2016 (which either party may extend to March 31, 2017 if the only closing condition that has not been met is that related to the readiness of the Spin-Off ); (3) if there is a permanent, non-appealable injunction or law restraining or prohibiting the consummation of the Merger; (4) if either party’s stockholders fail to approve the transactions; (5) if the other party’s Board of Directors changes its recommendation in favor of the transactions; (6) if the other party has materially breached its non-solicit covenant, subject to a cure period; (7) in order to enter into a superior proposal (as defined in the Merger Agreement, subject to compliance with certain terms and conditions included in the Merger Agreement); or (8) if the other party has breached its representations or covenants in a way that prevents satisfaction of a closing condition, subject to a cure period.

If the Merger Agreement is terminated because (1) a party’s Board of Directors changes its recommendation in favor of the transactions contemplated by the Merger Agreement; (2) a party terminates the agreement to enter into a superior proposal; (3) a party breaches its non-solicit covenant; or (4) a party consummates or enters into an agreement for an alternative transaction within twelve months following termination under certain circumstances, such party must pay a termination fee of the lesser of $65 million or the maximum amount that could be paid to the other party without causing it to fail to meet the REIT requirements for such year. The Merger Agreement also provides that a party must pay the other party an expense reimbursement of the lesser of $20 million and the maximum amount that can be paid to the other party without causing it to fail to meet the REIT requirements for such year, if the Merger Agreement is terminated because such party’s stockholders vote against the transactions contemplated by the Merger Agreement. Any unpaid amount of the foregoing fees (due to limitations of REIT requirements) will be escrowed and paid out over a five-year period. The expense reimbursement will be set off against the termination fee if the termination fee later becomes payable.

The Merger and Spin-Off are currently anticipated to close in the fourth quarter of 2016.