Commitments and Contingencies - Construction Activity (Details) $ in Millions	Jun. 30, 2017 USD ($) ft²
Other Commitments [Line Items]
Approximate Square Feet | ft²	14,500,000
Medical Office Building Expansion | TENNESSEE
Other Commitments [Line Items]
Approximate Square Feet | ft²	70,000
Total amount funded	$ 10.3
Tenant improvements included in construction funded	3.1
Construction activity, estimated remaining fundings	$ 2.2
Medical Office Building | COLORADO
Other Commitments [Line Items]
Approximate Square Feet | ft²	99,957
Total amount funded	$ 21.6
Estimated total investment	$ 26.5