Commitments and Contingencies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) ft² land_parcel	Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Approximate square feet | ft²	15,400,000
Number of land parcels held for development | land_parcel	7
Investment in land held for development	$ 24,600	$ 24,600
First and Second Generation Leases [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Anticipated amount of investment	$ 46,600
Medical Office Building Expansion [Member] | North Carolina [Member]
Property, Plant and Equipment [Line Items]
Approximate square feet | ft²	40,278
Medical Office Building [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 34,243
Approximate square feet | ft²	261,883
Medical Office Building [Member] | North Carolina [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 1,500
Medical Office Building [Member] | Memphis, Tennessee [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 9,032
Approximate square feet | ft²	110,883
Total funding during the year, excluding purchase of land and building	$ 300
Medical Office Building [Member] | Memphis, Tennessee [Member] | Land and Building [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	8,700
Medical Office Building [Member] | Nashville, Tennessee [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	1,000
Medical Office Building [Member] | Washington [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 25,211
Approximate square feet | ft²	151,000
Medical Office Building [Member] | Colorado [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 600