2018 Acquisitions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Number of real estate properties	1,200
Payments to acquire real estate | $	$ 958,125	$ 265,907	$ 664,684
2018 Acquisitions
Business Acquisition [Line Items]
Payments to acquire real estate | $		$ 311,300
2018 Acquisitions | Office Operations
Business Acquisition [Line Items]
Number of real estate properties		5
2018 Acquisitions | Office Operations | Medical Office Buildings
Business Acquisition [Line Items]
Number of real estate properties		4
2018 Acquisitions | Office Operations | Research and Innovation Center
Business Acquisition [Line Items]
Number of real estate properties		1
2018 Acquisitions | Senior Living Operations | Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties		1