Acquisitions and Dispositions - Disposition (Details) - Disposal Group, Disposed of by Sale, Not Discontinued Operations - Georgia Portfolio $ in Thousands		3 Months Ended		6 Months Ended
	Feb. 23, 2017 USD ($) ft² buildings	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)
Business Acquisition [Line Items]
Number of medical office buildings | buildings	4
Square feet of building being disposed | ft²	80,292
Proceeds from divestiture of businesses	$ 18,200
Gain on disposal	$ 5,300	$ 5,303	$ 0	$ 5,303	$ 0
Revenues		19	417	438	833
Income before gain on sale of investment properties:		(53)	109	87	196
Net income (loss)		$ 5,250	$ 109	$ 5,390	$ 196