Commitments and Contingencies - Construction Activity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) ft² property	Dec. 31, 2015 USD ($) ft²	Dec. 31, 2006 USD ($)
Other Commitments [Line Items]
Approximate Square Feet | ft²	14,500,000
Land held for redevelopment	$ 17,438	$ 17,452
ALABAMA
Other Commitments [Line Items]
Total Amount Funded	14,800
Estimated Remaining Fundings	600
Estimated Total Investment	$ 15,400
TEXAS
Other Commitments [Line Items]
Number of Properties | property	2
Estimated Remaining Fundings	$ 500
TENNESSEE
Other Commitments [Line Items]
Number of Properties | property	2
Total Amount Funded	$ 45,800
Estimated Total Investment	51,800
Land held for redevelopment	$ 4,300
Medical Office Building Expansion [Member] | TENNESSEE
Other Commitments [Line Items]
Approximate Square Feet | ft²	70,000
Retail Site [Member] | TEXAS
Other Commitments [Line Items]
Total Amount Funded	$ 5,100
Estimated Total Investment	$ 5,600
Approximate Square Feet | ft²		12,900
Land held for redevelopment			$ 1,500
Percentage of property leased	100.00%
Medical Office Building [Member] | TENNESSEE
Other Commitments [Line Items]
Number of Properties | property	2
Construction in Progress, Gross	$ 38,346
Other Amounts Funded	7,429
Total Amount Funded	45,775
Estimated Remaining Fundings	6,025
Estimated Total Investment	$ 51,800
Approximate Square Feet | ft²	294,000
Medical Office Building [Member] | COLORADO
Other Commitments [Line Items]
Number of Properties | property	1
Construction in Progress, Gross	$ 7,388
Other Amounts Funded	0
Total Amount Funded	7,388
Estimated Remaining Fundings	19,112
Estimated Total Investment	$ 26,500
Approximate Square Feet | ft²	98,000
Medical Office Buildings and Retail Sites [Member]
Other Commitments [Line Items]
Construction in Progress, Gross	$ 45,734
Other Amounts Funded	7,429
Total Amount Funded	53,163
Estimated Remaining Fundings	25,137
Estimated Total Investment	$ 78,300
Approximate Square Feet | ft²	392,000