Impairment and Dispositions (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Aug. 03, 2018 USD ($) ft² building	Jun. 30, 2018 USD ($) property	Jun. 30, 2017 USD ($) building	Jun. 30, 2018 USD ($) building property	Jun. 30, 2017 USD ($) ft²	Dec. 31, 2017 property Buildings
Real Estate [Line Items]
Impairment		$ 0	$ 5,093	$ 4,606	$ 5,093
Number of disposed assets			1	2		2
Proceeds from the sale of real estate					$ 5,000
Gross leasable area of real estate disposed (in square feet) | ft²					48,000
Disposal Group, Held-for-sale, Not Discontinued Operations
Real Estate [Line Items]
Number of properties Held-for-sale | property		1		1		0
Subsequent Event
Real Estate [Line Items]
Number of disposed assets | building	16
Proceeds from the sale of real estate	$ 285,000
Gross leasable area of real estate disposed (in square feet) | ft²	856,000
Gross sales price on property sale	$ 9,300
Medical Office Buildings in Texas and South Carolina
Real Estate [Line Items]
Impairment				$ 4,600
Aggregate value of impaired MOBs		$ 13,000		$ 13,000