Acquisitions and Dispositions - Dispositions (Details) $ in Thousands					12 Months Ended
	Jul. 27, 2018 USD ($) states healthcareproperty	Jun. 28, 2018 USD ($) states buildings	Mar. 30, 2018 USD ($) healthcareproperty	Feb. 16, 2018 USD ($) healthcareproperty	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) states	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Number of states in which operating healthcare properties and land parcel located | states						15
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Business Acquisition [Line Items]
Number of medical office buildings	17	15	1	1
Aggregate purchase price	$ 127,200	$ 90,700	$ 1,100	$ 1,400
Number of states in which operating healthcare properties and land parcel located | states	7	3
Gain on sale of investment properties, net	$ 14,200	$ (2,600)	$ 100	$ 100
2018 Dispositions | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Business Acquisition [Line Items]
Revenue					$ 12,287	$ 23,960	$ 24,090
Income before gain on sale of investment properties, net					5,027	5,765	7,142
Gain on sale of investment properties, net					11,664	0	0
Net income					16,691	5,765	7,142
2017 Dispositions | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Business Acquisition [Line Items]
Revenue					0	823	1,967
Income before gain on sale of investment properties, net					0	108	433
Gain on sale of investment properties, net					0	5,870	0
Net income					$ 0	$ 5,978	$ 433