Concentration	3 Months Ended
Mar. 31, 2017
Risks and Uncertainties [Abstract]
Concentration	Concentration Tenant and Credit Concentration We define annualized rental income as the annualized contractual base rents from our tenants pursuant to our lease agreements as of the measurement date, plus straight line rent adjustments and estimated recurring expense reimbursements to be paid to us, and excluding lease value amortization. The U.S. Government, 13 state governments, and four other government tenants combined were responsible for 87.9% and 92.8% of our annualized rental income, excluding one property (one building) classified as discontinued operations, as of March 31, 2017 and 2016, respectively. The U.S. Government is our largest tenant by annualized rental income and was responsible for 60.1% and 64.6% of our annualized rental income, excluding one property classified as discontinued operations, as of March 31, 2017 and 2016, respectively. Geographic Concentration At March 31, 2017, our 74 properties (96 buildings), excluding one property (one building) classified as discontinued operations, were located in 31 states and the District of Columbia. Properties located in Virginia, California, the District of Columbia, Georgia, New York, Maryland and Massachusetts were responsible for 14.8%, 14.4%, 9.5%, 8.6%, 7.6%, 7.1% and 4.9% of our annualized rental income as of March 31, 2017, respectively.

Concentration

3 Months Ended

Mar. 31, 2017

Tenant and Credit Concentration

We define annualized rental income as the annualized contractual base rents from our tenants pursuant to our lease agreements as of the measurement date, plus straight line rent adjustments and estimated recurring expense reimbursements to be paid to us, and excluding lease value amortization. The U.S. Government, 13 state governments, and four other government tenants combined were responsible for 87.9% and 92.8% of our annualized rental income, excluding one property (one building) classified as discontinued operations, as of March 31, 2017 and 2016, respectively. The U.S. Government is our largest tenant by annualized rental income and was responsible for 60.1% and 64.6% of our annualized rental income, excluding one property classified as discontinued operations, as of March 31, 2017 and 2016, respectively.

Geographic Concentration

At March 31, 2017, our 74 properties (96 buildings), excluding one property (one building) classified as discontinued operations, were located in 31 states and the District of Columbia. Properties located in Virginia, California, the District of Columbia, Georgia, New York, Maryland and Massachusetts were responsible for 14.8%, 14.4%, 9.5%, 8.6%, 7.6%, 7.1% and 4.9% of our annualized rental income as of March 31, 2017, respectively.