Indebtedness	3 Months Ended
Mar. 31, 2018
Debt Disclosure [Abstract]
Indebtedness	Indebtedness Unsecured Revolving Credit Facility and Term Loan: We are party to a credit agreement pursuant to which the lenders agreed to provide a $750.0 million unsecured revolving credit facility, a $200.0 million 5-year term loan facility, and a $200.0 million 7-year term loan facility. 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 7.5 basis points 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. 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 105 basis points as of March 31, 2018. As of March 31, 2018, the interest rate payable on borrowings under our revolving credit facility was 2.93%. As of March 31, 2018, we had no balance outstanding and $750.0 million available under our revolving credit facility and the facility fee as of March 31, 2018 was 20 basis points. Our term loans currently bear interest at a rate of LIBOR plus a spread, which was 115 and 155 basis points for the 5-year and 7-year term loan, respectively, as of March 31, 2018. As of March 31, 2018, the interest rates for the amounts outstanding under our 5-year term loan and 7-year term loan were 3.03% and 3.43%, respectively. As of March 31, 2018, 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 and our credit 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 March 31, 2018, we believe we were in compliance with all of our respective covenants under our public debt indenture and related supplements and our credit agreement. Senior Unsecured Notes: At March 31, 2018, we had senior unsecured notes of $250.0 million (excluding net discounts and unamortized deferred financing fees) maturing in 2020. On March 7, 2018, we redeemed at par all $175.0 million of our 5.75% senior unsecured notes due 2042 and recognized a loss on early extinguishment of debt of $4.9 million from the write off of unamortized deferred financing fees. Mortgage Notes Payable: At March 31, 2018, two of our properties with an aggregate net book value of $51.9 million had secured mortgage notes totaling $32.3 million (including net premiums and unamortized deferred financing fees) maturing from 2021 through 2026.

Indebtedness

Unsecured Revolving Credit Facility and Term Loan:

We are party to a credit agreement pursuant to which the lenders agreed to provide a $750.0 million unsecured revolving credit facility, a $200.0 million 5-year term loan facility, and a $200.0 million 7-year term loan facility. 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 7.5 basis points 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.

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 105 basis points as of March 31, 2018. As of March 31, 2018, the interest rate payable on borrowings under our revolving credit facility was 2.93%. As of March 31, 2018, we had no balance outstanding and $750.0 million available under our revolving credit facility and the facility fee as of March 31, 2018 was 20 basis points. Our term loans currently bear interest at a rate of LIBOR plus a spread, which was 115 and 155 basis points for the 5-year and 7-year term loan, respectively, as of March 31, 2018. As of March 31, 2018, the interest rates for the amounts outstanding under our 5-year term loan and 7-year term loan were 3.03% and 3.43%, respectively. As of March 31, 2018, 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 and our credit 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 March 31, 2018, we believe we were in compliance with all of our respective covenants under our public debt indenture and related supplements and our credit agreement.

Senior Unsecured Notes:

At March 31, 2018, we had senior unsecured notes of $250.0 million (excluding net discounts and unamortized deferred financing fees) maturing in 2020.

On March 7, 2018, we redeemed at par all $175.0 million of our 5.75% senior unsecured notes due 2042 and recognized a loss on early extinguishment of debt of $4.9 million from the write off of unamortized deferred financing fees.

Mortgage Notes Payable:

At March 31, 2018, two of our properties with an aggregate net book value of $51.9 million had secured mortgage notes totaling $32.3 million (including net premiums and unamortized deferred financing fees) maturing from 2021 through 2026.