Commitments and Contingencies - Construction Activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) ft² property
Other Commitments [Line Items]
NUMBER OF PROP. | property	204
Approximate square feet | ft²	15,400,000
Medical Office Building [Member]
Other Commitments [Line Items]
CONSTRUCTION IN PROGRESS BALANCE	$ 48,731
TOTAL FUNDED during the year	34,243
Total Amount Funded	58,065
ESTIMATED REMAINING FUNDINGS unaudited	33,855
ESTIMATED TOTAL INVESTMENT unaudited	$ 91,920
Approximate square feet | ft²	261,883
Washington [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
NUMBER OF PROP. | property	1
CONSTRUCTION IN PROGRESS BALANCE	$ 48,731
TOTAL FUNDED during the year	25,211
Total Amount Funded	49,033
ESTIMATED REMAINING FUNDINGS unaudited	15,087
ESTIMATED TOTAL INVESTMENT unaudited	$ 64,120
Approximate square feet | ft²	151,000
Memphis, Tennessee [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
NUMBER OF PROP. | property	1
CONSTRUCTION IN PROGRESS BALANCE	$ 0
TOTAL FUNDED during the year	9,032
Total Amount Funded	9,032
ESTIMATED REMAINING FUNDINGS unaudited	18,768
ESTIMATED TOTAL INVESTMENT unaudited	$ 27,800
Approximate square feet | ft²	110,883