Indebtedness	9 Months Ended
Sep. 30, 2015
Debt Disclosure [Abstract]
Indebtedness	Indebtedness Unsecured Revolving Credit Facility and Term Loan: Prior to January 29, 2015, we had a $750.0 million unsecured revolving credit facility. The unsecured revolving credit facility was set to mature on October 19, 2015, and had an interest rate of LIBOR plus a spread, which was 150 basis points as of December 31, 2014. We paid a facility fee of 35 basis points per annum on the total amount of lending commitments under our revolving credit facility. Prior to January 29, 2015, we also had a $400.0 million unsecured term loan that was set to mature on December 15, 2016. Our term loan had an interest rate of LIBOR plus a spread, which was 185 basis points as of December 31, 2014. On January 29, 2015, we entered into a new credit agreement, pursuant to which the lenders agreed to provide (i) a $750.0 million unsecured revolving credit facility, (ii) a $200.0 million 5-year term loan facility and (iii) a $200.0 million 7-year term loan facility. The new agreement replaced our prior credit agreement, dated as of August 9, 2010, and our prior term loan agreement, dated as of December 16, 2010. In connection with the new agreement, we recognized a loss on early extinguishment of debt of $0.4 million from the write-off of unamortized deferred financing fees for the nine months ended September 30, 2015. The revolving credit facility has a scheduled maturity date of January 28, 2019, which maturity date may be extended for up to two additional periods of six months at our option subject to satisfaction of certain conditions and the payment of an extension fee of 0.075% of the aggregate amount available under the revolving credit facility. The 5-year term loan and the 7-year term loan have scheduled maturity dates of January 28, 2020 and January 28, 2022, respectively. We used the proceeds of borrowings under the credit agreement to repay all amounts outstanding and due under the previous term loan agreement. The credit agreement permits us to utilize up to $100.0 million of the revolving credit facility for the issuance of letters of credit. Amounts outstanding under the credit agreement generally may be prepaid at any time without premium or penalty, subject to certain exceptions. We have the right to request increases in the aggregate maximum amount of borrowings available under the revolving credit facility and term loans up to an additional $1.15 billion, subject to certain conditions. Borrowings under the 5-year term loan and 7-year term loan will, subject to certain exceptions, bear interest at a LIBOR rate plus a margin of 90 to 180 basis points for the 5-year term loan and 140 to 235 basis points for the 7-year term loan, in each case depending on our credit rating. Borrowings under the revolving credit facility will, subject to certain exceptions, bear interest at a rate equal to, at our option, either a LIBOR rate or a base rate plus a margin of 87.5 to 155 basis points for LIBOR rate advances and 0 to 55 basis points for base rate advances, in each case depending on our credit rating. In addition, we are required to pay a facility fee of 12.5 to 30 basis points, depending on our credit rating, on the borrowings available under the revolving credit facility, whether or not utilized. Borrowings under our revolving credit facility currently bear interest at LIBOR plus a spread, which was 125 basis points as of September 30, 2015. As of September 30, 2015, the interest rate payable on borrowings under our revolving credit facility was 1.44%. As of September 30, 2015, we had no balance outstanding and $750.0 million available under our revolving credit facility. Our term loans currently bear interest at a rate of LIBOR plus a spread, which was 140 and 180 basis points for the 5-year and 7-year term loan, respectively, as of September 30, 2015. As of September 30, 2015, the interest rates for the amounts outstanding under our 5-year term loan and 7-year term loan were 1.59% and 1.99%, respectively. As of September 30, 2015, we had $200.0 million outstanding under each of our 5-year and 7-year term loans. Debt Covenants: Our public debt indenture and related supplements, our revolving credit facility agreement and our term loan agreement contain a number of financial and other covenants, including covenants that restrict our ability to incur indebtedness or to make distributions under certain circumstances and require us to maintain financial ratios and a minimum net worth. At September 30, 2015, we believe we were in compliance with all of our respective covenants under our public debt indenture and related supplements, our revolving credit facility and our term loan agreements. Senior Unsecured Notes: On May 1, 2015, we redeemed at par $138.8 million of our 5.75% senior unsecured notes due 2015 and recognized a loss on early extinguishment of debt of $0.1 million from the write-off of an unamortized discount and unamortized deferred financing fees. Mortgage Notes Payable: At September 30, 2015, six of our properties (10 buildings) with an aggregate net book value of $452.4 million had secured mortgage notes totaling $367.7 million (including net premiums and discounts) maturing from 2016 through 2026. During the quarter ended June 30, 2014, we made the decision to cease making loan servicing payments on 225 Water Street in Jacksonville, Florida. The first payment we determined not to make for this property was due on June 11, 2014. The property was secured by a non-recourse mortgage loan. On October 10, 2014, we were notified by the lender that our decision to cease making loan servicing payments created an event of default effective July 11, 2014, and the lender exercised its option to accelerate the maturity of the unpaid balance of the loan. Beginning July 11, 2014, we accrued interest on this loan at 10.03%, to include the 4.0% of default interest. The lender filed a suit of foreclosure for this property and we cooperated with the lender to allow for a consensual foreclosure process. On May 22, 2015, title to 225 Water Street was transferred to the lender pursuant to the consensual foreclosure in full satisfaction of the mortgage debt, with a principal balance of $40.1 million. The transaction resulted in a gain on early extinguishment of debt of $17.3 million for the excess of the debt principal balance over the net book value of the property for the nine months ended September 30, 2015. In accordance with the agreement to sell 1320 Main Street, we were required to deliver the property unencumbered. On June 3, 2015, prior to the sale, we defeased the $38.7 million outstanding balance of the mortgage loan secured by 1320 Main Street. The defeasance costs and write off of the unamortized deferred financing costs, net of the write off of the unamortized premium, resulted in a net loss on early extinguishment of debt of $6.2 million for the nine months ended September 30, 2015. In accordance with the agreement to sell 2501 20th Place South, we were required to deliver the property unencumbered. On June 5, 2015, we prepaid $10.0 million of 7.36% mortgage debt at 2501 20th Place South and recognized a loss on early extinguishment of debt totaling $0.6 million for the nine months ended September 30, 2015, which consisted of a prepayment premium and the write off of unamortized deferred financing fees, net of the write off of an unamortized premium. In accordance with the agreement to sell Illinois Center, we were required to deliver the property unencumbered. On August 3, 2015, prior to the sale, we defeased the outstanding $141.4 million balance of the mortgage loan secured by 111 East Wacker Drive, one of the buildings included in Illinois Center. The defeasance costs and write off of the unamortized deferred financing costs, net of the write off of the unamortized premium, resulted in a net loss on early extinguishment of debt of $3.9 million for the three and nine months ended September 30, 2015.

Indebtedness

Unsecured Revolving Credit Facility and Term Loan:

Prior to January 29, 2015, we had a $750.0 million unsecured revolving credit facility. The unsecured revolving credit facility was set to mature on October 19, 2015, and had an interest rate of LIBOR plus a spread, which was 150 basis points as of December 31, 2014. We paid a facility fee of 35 basis points per annum on the total amount of lending commitments under our revolving credit facility. Prior to January 29, 2015, we also had a $400.0 million unsecured term loan that was set to mature on December 15, 2016. Our term loan had an interest rate of LIBOR plus a spread, which was 185 basis points as of December 31, 2014.

On January 29, 2015, we entered into a new credit agreement, pursuant to which the lenders agreed to provide (i) a $750.0 million unsecured revolving credit facility, (ii) a $200.0 million 5-year term loan facility and (iii) a $200.0 million 7-year term loan facility. The new agreement replaced our prior credit agreement, dated as of August 9, 2010, and our prior term loan agreement, dated as of December 16, 2010. In connection with the new agreement, we recognized a loss on early extinguishment of debt of $0.4 million from the write-off of unamortized deferred financing fees for the nine months ended September 30, 2015. The revolving credit facility has a scheduled maturity date of January 28, 2019, which maturity date may be extended for up to two additional periods of six months at our option subject to satisfaction of certain conditions and the payment of an extension fee of 0.075% of the aggregate amount available under the revolving credit facility. The 5-year term loan and the 7-year term loan have scheduled maturity dates of January 28, 2020 and January 28, 2022, respectively. We used the proceeds of borrowings under the credit agreement to repay all amounts outstanding and due under the previous term loan agreement.

The credit agreement permits us to utilize up to $100.0 million of the revolving credit facility for the issuance of letters of credit. Amounts outstanding under the credit agreement generally may be prepaid at any time without premium or penalty, subject to certain exceptions. We have the right to request increases in the aggregate maximum amount of borrowings available under the revolving credit facility and term loans up to an additional $1.15 billion, subject to certain conditions.

Borrowings under the 5-year term loan and 7-year term loan will, subject to certain exceptions, bear interest at a LIBOR rate plus a margin of 90 to 180 basis points for the 5-year term loan and 140 to 235 basis points for the 7-year term loan, in each case depending on our credit rating. Borrowings under the revolving credit facility will, subject to certain exceptions, bear interest at a rate equal to, at our option, either a LIBOR rate or a base rate plus a margin of 87.5 to 155 basis points for LIBOR rate advances and 0 to 55 basis points for base rate advances, in each case depending on our credit rating. In addition, we are required to pay a facility fee of 12.5 to 30 basis points, depending on our credit rating, on the borrowings available under the revolving credit facility, whether or not utilized.

Borrowings under our revolving credit facility currently bear interest at LIBOR plus a spread, which was 125 basis points as of September 30, 2015. As of September 30, 2015, the interest rate payable on borrowings under our revolving credit facility was 1.44%. As of September 30, 2015, we had no balance outstanding and $750.0 million available under our revolving credit facility. Our term loans currently bear interest at a rate of LIBOR plus a spread, which was 140 and 180 basis points for the 5-year and 7-year term loan, respectively, as of September 30, 2015. As of September 30, 2015, the interest rates for the amounts outstanding under our 5-year term loan and 7-year term loan were 1.59% and 1.99%, respectively. As of September 30, 2015, we had $200.0 million outstanding under each of our 5-year and 7-year term loans.

Debt Covenants:

Our public debt indenture and related supplements, our revolving credit facility agreement and our term loan agreement contain a number of financial and other covenants, including covenants that restrict our ability to incur indebtedness or to make distributions under certain circumstances and require us to maintain financial ratios and a minimum net worth. At September 30, 2015, we believe we were in compliance with all of our respective covenants under our public debt indenture and related supplements, our revolving credit facility and our term loan agreements.

Senior Unsecured Notes:

On May 1, 2015, we redeemed at par $138.8 million of our 5.75% senior unsecured notes due 2015 and recognized a loss on early extinguishment of debt of $0.1 million from the write-off of an unamortized discount and unamortized deferred financing fees.

Mortgage Notes Payable:

At September 30, 2015, six of our properties (10 buildings) with an aggregate net book value of $452.4 million had secured mortgage notes totaling $367.7 million (including net premiums and discounts) maturing from 2016 through 2026.

During the quarter ended June 30, 2014, we made the decision to cease making loan servicing payments on 225 Water Street in Jacksonville, Florida. The first payment we determined not to make for this property was due on June 11, 2014. The property was secured by a non-recourse mortgage loan. On October 10, 2014, we were notified by the lender that our decision to cease making loan servicing payments created an event of default effective July 11, 2014, and the lender exercised its option to accelerate the maturity of the unpaid balance of the loan. Beginning July 11, 2014, we accrued interest on this loan at 10.03%, to include the 4.0% of default interest. The lender filed a suit of foreclosure for this property and we cooperated with the lender to allow for a consensual foreclosure process. On May 22, 2015, title to 225 Water Street was transferred to the lender pursuant to the consensual foreclosure in full satisfaction of the mortgage debt, with a principal balance of $40.1 million. The transaction resulted in a gain on early extinguishment of debt of $17.3 million for the excess of the debt principal balance over the net book value of the property for the nine months ended September 30, 2015.

In accordance with the agreement to sell 1320 Main Street, we were required to deliver the property unencumbered. On June 3, 2015, prior to the sale, we defeased the $38.7 million outstanding balance of the mortgage loan secured by 1320 Main Street. The defeasance costs and write off of the unamortized deferred financing costs, net of the write off of the unamortized premium, resulted in a net loss on early extinguishment of debt of $6.2 million for the nine months ended September 30, 2015.

In accordance with the agreement to sell 2501 20th Place South, we were required to deliver the property unencumbered. On June 5, 2015, we prepaid $10.0 million of 7.36% mortgage debt at 2501 20th Place South and recognized a loss on early extinguishment of debt totaling $0.6 million for the nine months ended September 30, 2015, which consisted of a prepayment premium and the write off of unamortized deferred financing fees, net of the write off of an unamortized premium.

In accordance with the agreement to sell Illinois Center, we were required to deliver the property unencumbered. On August 3, 2015, prior to the sale, we defeased the outstanding $141.4 million balance of the mortgage loan secured by 111 East Wacker Drive, one of the buildings included in Illinois Center. The defeasance costs and write off of the unamortized deferred financing costs, net of the write off of the unamortized premium, resulted in a net loss on early extinguishment of debt of $3.9 million for the three and nine months ended September 30, 2015.