Subsequent Events	12 Months Ended
Dec. 31, 2016
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	21. SUBSEQUENT EVENTS Concord Airport Plaza Sale On February 2, 2017, the Company completed the disposition of two office properties located at 1200 and 1220 Concord Avenue, in Concord, California, containing 350,256 net rentable square feet, for a gross sales price of $33.1 million. As the properties were impaired to fair value during the fourth quarter of 2016, there is an estimated gain of $0.5 million on sale. The sale is designated as a like-kind exchange under Section 1031 of the Internal Revenue Code (“IRC”) and, as such, the proceeds, totaling $32.0 million after closing costs and prorations, were delivered to a Qualified Intermediary, as defined under the IRC. The Parc at Plymouth Meeting Venture Sale On January 31, 2017, the Company sold its 50% interest in TB-BDN Plymouth Apartments, L.P., a 50/50 real estate venture with Toll Brothers, at a gross sales value of $100.5 million. The venture developed and operates a 398-unit multi-family complex in Plymouth Meeting, Pennsylvania encumbered by a $54.0 million construction loan. The construction loan was repaid commensurate with the sale of the Company’s 50% interest. As a result, the Company is no longer subject to a $3.2 million payment guarantee on the construction loan. The cash proceeds, after the payment of the Company’s share of the debt and closing costs, was $27.2 million. As the carrying amount of the Company’s investment at the time of sale is $23.3 million, the estimated gain is $14.6 million. Garza Land Sale On January 30, 2017, the Company disposed of 1.7 acres of land located in Austin, Texas, known as the Garza Ranch, for a sales price of $3.5 million. The land did not meet the criteria to be classified as a sale as of December 31, 2016. The Company has a continuing involvement through a completion guaranty, which requires the Company as developer to complete certain infrastructure improvements on behalf of the buyers of the land parcels. The cash received at settlement was recorded as “deferred income, gains and rent” on the Company’s balance sheet and the Company will recognize the sale once the infrastructure improvements are complete. At-the-Market Offering On January 10, 2017, the Company entered into a continuous offering program, under which it may sell up to an aggregate of 16,000,000 common shares until January 10, 2020 in at the market offerings. This program is a replacement of a prior continuous offering program that expired on November 3, 2016. The Company did not sell any shares under the prior program during 2016 and has not sold any shares under the new program through the date of this report.

21. SUBSEQUENT EVENTS

Concord Airport Plaza Sale

On February 2, 2017, the Company completed the disposition of two office properties located at 1200 and 1220 Concord Avenue, in Concord, California, containing 350,256 net rentable square feet, for a gross sales price of $33.1 million. As the properties were impaired to fair value during the fourth quarter of 2016, there is an estimated gain of $0.5 million on sale.

The sale is designated as a like-kind exchange under Section 1031 of the Internal Revenue Code (“IRC”) and, as such, the proceeds, totaling $32.0 million after closing costs and prorations, were delivered to a Qualified Intermediary, as defined under the IRC.

The Parc at Plymouth Meeting Venture Sale

On January 31, 2017, the Company sold its 50% interest in TB-BDN Plymouth Apartments, L.P., a 50/50 real estate venture with Toll Brothers, at a gross sales value of $100.5 million. The venture developed and operates a 398-unit multi-family complex in Plymouth Meeting, Pennsylvania encumbered by a $54.0 million construction loan. The construction loan was repaid commensurate with the sale of the Company’s 50% interest. As a result, the Company is no longer subject to a $3.2 million payment guarantee on the construction loan. The cash proceeds, after the payment of the Company’s share of the debt and closing costs, was $27.2 million. As the carrying amount of the Company’s investment at the time of sale is $23.3 million, the estimated gain is $14.6 million.

Garza Land Sale

On January 30, 2017, the Company disposed of 1.7 acres of land located in Austin, Texas, known as the Garza Ranch, for a sales price of $3.5 million. The land did not meet the criteria to be classified as a sale as of December 31, 2016. The Company has a continuing involvement through a completion guaranty, which requires the Company as developer to complete certain infrastructure improvements on behalf of the buyers of the land parcels. The cash received at settlement was recorded as “deferred income, gains and rent” on the Company’s balance sheet and the Company will recognize the sale once the infrastructure improvements are complete.

At-the-Market Offering

On January 10, 2017, the Company entered into a continuous offering program, under which it may sell up to an aggregate of 16,000,000 common shares until January 10, 2020 in at the market offerings. This program is a replacement of a prior continuous offering program that expired on November 3, 2016. The Company did not sell any shares under the prior program during 2016 and has not sold any shares under the new program through the date of this report.