Related Person Transactions	12 Months Ended
Dec. 31, 2017
Related Party Transactions [Abstract]
Related Person Transactions	Related Person Transactions The following discussion includes a description of our related person transactions for the years ended December 31, 2017, 2016 and 2015. Two North Riverside Plaza Joint Venture Limited Partnership and Equity Group Investments and associated entities: Effective July 20, 2015, we entered into a lease with Two North Riverside Plaza Joint Venture Limited Partnership, an entity associated with Mr. Zell, our Chairman, to occupy office space on the twentieth and twenty-first floors of Two North Riverside Plaza in Chicago, Illinois (20th/21st Floor Office Lease). The initial term of the lease is approximately five years, with one 5-year renewal option. We completed improvements to the office space utilizing the $0.7 million tenant improvement allowance pursuant to the lease. In connection with the 20th/21st Floor Office Lease, we also have a lease with Two North Riverside Plaza Joint Venture Limited Partnership for storage space in the basement of Two North Riverside Plaza. The lease expires December 31, 2020; however, each party has the right to terminate on 30 days' prior written notice. During the years ended December 31, 2017 and 2016, we recognized expense of $0.8 million and $0.8 million, respectively, pursuant to the 20th/21st Floor Office Lease and the related storage space. The future minimum lease payments scheduled to be paid by us during the current terms of this lease as of December 31, 2017 are as follows: $0.9 million in 2018, $0.9 million in 2019 and $0.9 million in 2020. As of December 31, 2017 and 2016, we had $0.0 million and $0.1 million, respectively, due to Two North Riverside Plaza Joint Venture Limited Partnership pursuant to the 20th/21st Floor Office Lease and the related storage space. We had a license agreement with Equity Group Investments, a private investment firm (Equity Group), to use office space on the sixth floor at Two North Riverside Plaza. The license fee included the non-exclusive use of additional areas on the sixth floor (such as conference rooms and common areas), certain administrative services (such as mail room services and reception desk staffing), office equipment, office furniture, supplies, licensee’s share of building operating expenses and real estate taxes and access to one parking space. Mr. Zell, our Chairman, is the Chairman and Chief Executive Officer of Equity Group, and Mr. Helfand, our President and Chief Executive Officer, is the Co-President of Equity Group. The license agreement was terminated as of December 30, 2015. During the year ended December 31, 2015, we recognized expense of $0.2 million pursuant to the license agreement. We had a one-year lease with one 3-month renewal option with Two North Riverside Plaza Joint Venture Limited Partnership to occupy office space on the fourteenth floor at Two North Riverside Plaza. This lease was terminated, effective January 31, 2015. During the year ended December 31, 2015, we recognized expense of $13,000 pursuant to the office space on the fourteenth floor. We had a sublease with Equity Residential Management, L.L.C., an entity associated with Mr Zell, our Chairman, to occupy office space on the tenth floor of Two North Riverside Plaza. Equity Residential Management, L.L.C. leases the space from Two North Riverside Plaza Joint Venture Limited Partnership. The sublease agreement was terminated as of December 30, 2015. During the year ended December 31, 2015, we recognized expense of $0.4 million pursuant to the tenth floor office sublease. Related/Corvex: On July 31, 2014, at the reconvened session of our 2014 annual meeting of shareholders, our shareholders voted to approve the reimbursement of approximately $33.5 million of verified expenses incurred by Related Fund Management, LLC and Corvex Management LP (Related/Corvex) in connection with their consent solicitations to remove our former Trustees and elect the new Board of Trustees and to engage in related litigation. Approximately $16.7 million was paid during the year ended December 31, 2014. Up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period after the date on which the reimbursement was approved by shareholders, and up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period between the first and second anniversaries of the date on which the reimbursement was approved by shareholders. The average closing price of our common shares was at least $26.00 during both the first and second one year periods after the date on which the reimbursement was approved by shareholders, and as a result, in August 2016 and 2015, we paid $8.2 million and $8.4 million, respectively, to Related/Corvex. Termination and Cooperation Agreement: Pursuant to a termination and cooperation agreement entered into with Reit Management & Research LLC (RMR) and RMR Australia Asset Management Pty Ltd (together, Former Manager), Former Manager agreed to use best efforts to assist us in the transition of our management and operations. We paid Former Manager $1.2 million per month for transition services from October 1, 2014 to February 28, 2015, which included continued management and other services for the Australian assets pursuant to an Australia management agreement. Beginning March 1, 2015, we agreed to pay Former Manager $0.1 million per month until we no longer required such services or until the Australia management agreement was terminated, which was terminated in the third quarter of 2015, effective October 31, 2015. There is no future obligation to pay any fees to Former Manager.

Related Person Transactions

The following discussion includes a description of our related person transactions for the years ended December 31, 2017, 2016 and 2015.

Two North Riverside Plaza Joint Venture Limited Partnership and Equity Group Investments and associated entities: Effective July 20, 2015, we entered into a lease with Two North Riverside Plaza Joint Venture Limited Partnership, an entity associated with Mr. Zell, our Chairman, to occupy office space on the twentieth and twenty-first floors of Two North Riverside Plaza in Chicago, Illinois (20th/21st Floor Office Lease). The initial term of the lease is approximately five years, with one 5-year renewal option. We completed improvements to the office space utilizing the $0.7 million tenant improvement allowance pursuant to the lease. In connection with the 20th/21st Floor Office Lease, we also have a lease with Two North Riverside Plaza Joint Venture Limited Partnership for storage space in the basement of Two North Riverside Plaza. The lease expires December 31, 2020; however, each party has the right to terminate on 30 days' prior written notice. During the years ended December 31, 2017 and 2016, we recognized expense of $0.8 million and $0.8 million, respectively, pursuant to the 20th/21st Floor Office Lease and the related storage space. The future minimum lease payments scheduled to be paid by us during the current terms of this lease as of December 31, 2017 are as follows: $0.9 million in 2018, $0.9 million in 2019 and $0.9 million in 2020. As of December 31, 2017 and 2016, we had $0.0 million and $0.1 million, respectively, due to Two North Riverside Plaza Joint Venture Limited Partnership pursuant to the 20th/21st Floor Office Lease and the related storage space.

We had a license agreement with Equity Group Investments, a private investment firm (Equity Group), to use office space on the sixth floor at Two North Riverside Plaza. The license fee included the non-exclusive use of additional areas on the sixth floor (such as conference rooms and common areas), certain administrative services (such as mail room services and reception desk staffing), office equipment, office furniture, supplies, licensee’s share of building operating expenses and real estate taxes and access to one parking space. Mr. Zell, our Chairman, is the Chairman and Chief Executive Officer of Equity Group, and Mr. Helfand, our President and Chief Executive Officer, is the Co-President of Equity Group. The license agreement was terminated as of December 30, 2015. During the year ended December 31, 2015, we recognized expense of $0.2 million pursuant to the license agreement.

We had a one-year lease with one 3-month renewal option with Two North Riverside Plaza Joint Venture Limited Partnership to occupy office space on the fourteenth floor at Two North Riverside Plaza. This lease was terminated, effective January 31, 2015. During the year ended December 31, 2015, we recognized expense of $13,000 pursuant to the office space on the fourteenth floor.

We had a sublease with Equity Residential Management, L.L.C., an entity associated with Mr Zell, our Chairman, to occupy office space on the tenth floor of Two North Riverside Plaza. Equity Residential Management, L.L.C. leases the space from Two North Riverside Plaza Joint Venture Limited Partnership. The sublease agreement was terminated as of December 30, 2015. During the year ended December 31, 2015, we recognized expense of $0.4 million pursuant to the tenth floor office sublease.

Related/Corvex: On July 31, 2014, at the reconvened session of our 2014 annual meeting of shareholders, our shareholders voted to approve the reimbursement of approximately $33.5 million of verified expenses incurred by Related Fund Management, LLC and Corvex Management LP (Related/Corvex) in connection with their consent solicitations to remove our former Trustees and elect the new Board of Trustees and to engage in related litigation. Approximately $16.7 million was paid during the year ended December 31, 2014. Up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period after the date on which the reimbursement was approved by shareholders, and up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period between the first and second anniversaries of the date on which the reimbursement was approved by shareholders. The average closing price of our common shares was at least $26.00 during both the first and second one year periods after the date on which the reimbursement was approved by shareholders, and as a result, in August 2016 and 2015, we paid $8.2 million and $8.4 million, respectively, to Related/Corvex.

Termination and Cooperation Agreement: Pursuant to a termination and cooperation agreement entered into with Reit Management & Research LLC (RMR) and RMR Australia Asset Management Pty Ltd (together, Former Manager), Former Manager agreed to use best efforts to assist us in the transition of our management and operations. We paid Former Manager $1.2 million per month for transition services from October 1, 2014 to February 28, 2015, which included continued management and other services for the Australian assets pursuant to an Australia management agreement. Beginning March 1, 2015, we agreed to pay Former Manager $0.1 million per month until we no longer required such services or until the Australia management agreement was terminated, which was terminated in the third quarter of 2015, effective October 31, 2015. There is no future obligation to pay any fees to Former Manager.