Commitments and Contingencies - Construction Activity (Details) ft² in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) ft² property	Dec. 31, 2015 property
Other Commitments [Line Items]
Number of Properties | property	202
Approximate Square Feet | ft²	14,600
Medical Office Buildings and Retail Sites [Member]
Other Commitments [Line Items]
Construction in Progress Balance	$ 11,655
Total Funded During the Year	40,220
Total Amount Funded	62,267
Estimated Remaining Fundings (unaudited)	20,853
Estimated Total Investment (unaudited)	$ 83,120
Approximate Square Feet | ft²	392
Tennessee [Member]
Other Commitments [Line Items]
Number of Properties | property		2
Total Amount Funded	$ 50,600
Tennessee [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
Number of Properties | property	2
Construction in Progress Balance	$ 0
Total Funded During the Year	28,794
Total Amount Funded	50,612
Estimated Remaining Fundings (unaudited)	6,008
Estimated Total Investment (unaudited)	$ 56,620
Approximate Square Feet | ft²	294
Colorado [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
Number of Properties | property	1
Construction in Progress Balance	$ 11,655
Total Funded During the Year	11,426
Total Amount Funded	11,655
Estimated Remaining Fundings (unaudited)	14,845
Estimated Total Investment (unaudited)	$ 26,500
Approximate Square Feet | ft²	98