Commitments and Contingencies - Construction Activity (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($) ft²
Other Commitments [Line Items]
Approximate square feet | ft²	15,500,000
Medical office building expansion | Memphis, Tennessee
Other Commitments [Line Items]
Approximate square feet | ft²	110,883
Medical office building | Memphis, Tennessee
Other Commitments [Line Items]
Construction activity, total funding during the period, excluding purchase of land and building	$ 2.3
Medical office building | Washington
Other Commitments [Line Items]
Approximate square feet | ft²	151,031
Total amount funded	$ 58.8
Estimated amount to complete project	5.3
Land and building | Medical office building | Memphis, Tennessee
Other Commitments [Line Items]
Construction activity, total funding during the period	$ 8.7