Acquisitions of Real Estate Property - 2018 Acquisitions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) property	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) property
Business Acquisition [Line Items]
Payments to acquire real estate | $	$ 78,648	$ 958,125	$ 265,907
Office operations
Business Acquisition [Line Items]
Number of real estate properties acquired			5
Seniors Housing Communities
Business Acquisition [Line Items]
Number of real estate properties acquired			1
Medical Office Buildings | Office operations
Business Acquisition [Line Items]
Number of real estate properties acquired			4
Research and Innovation Center | Office operations
Business Acquisition [Line Items]
Number of real estate properties acquired	2		1
2018 Acquisitions
Business Acquisition [Line Items]
Payments to acquire real estate | $			$ 311,300