Leases - Right-of-Use Assets and Lease Liabilities Related to Ground Leases (Details) - Ground $ in Millions	Jun. 30, 2019 USD ($)
Assets:
Right-of-use assets, at fair value	$ 26.7
Liabilities:
Ground lease liabilities, at fair value	$ 26.7
Key Terms
Weighted-average remaining lease term (years)	85 years 1 month 6 days
Weighted-average discount rate(1)	6.13%