Acquisitions and Dispositions - Summary of 2018 Acquisitions (Details) - USD ($) $ in Thousands							12 Months Ended
	Sep. 14, 2018	Apr. 03, 2018	Mar. 01, 2018	Feb. 16, 2018	Jan. 23, 2018	Jan. 09, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Acquisition price							$ 271,000	$ 1,414,179
Hazelwood Medical Commons
Business Acquisition [Line Items]
Acquisition price						$ 70,702
Lee's Hill Medical Plaza
Business Acquisition [Line Items]
Acquisition price					$ 28,000
Scottsdale, Arizona Land
Business Acquisition [Line Items]
Acquisition price				$ 700
Noncontrolling Interest Buyout - Minnesota portfolio
Business Acquisition [Line Items]
Noncontrolling interest, increase from business combination, percent							4.20%
Acquisition price			$ 6,406
Noncontrolling Interest, Ownership Percentage by Parent							99.60%
HMG Medical Plaza
Business Acquisition [Line Items]
Acquisition price		$ 71,295
Northside Medical Midtown MOB
Business Acquisition [Line Items]
Acquisition price	$ 82,147
Loan Investments
Business Acquisition [Line Items]
Acquisition price							$ 11,750