Commitments and Contingencies - Construction Activity (Details) $ in Millions	Sep. 30, 2018 USD ($) ft²
Other Commitments [Line Items]
Approximate Square Feet	14,800,000
Medical Office Building Expansion | NORTH CAROLINA
Other Commitments [Line Items]
Approximate Square Feet	38,000
Medical Office Building | NORTH CAROLINA
Other Commitments [Line Items]
Total amount funded | $	$ 9.2
Medical Office Building | COLORADO
Other Commitments [Line Items]
Approximate Square Feet	151,000
Total amount funded | $	$ 18.0