Commitments and Contingencies - Future Minimum Rental Payments Under Non-Cancelable Ground and Operating Leases (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 1,495
2019	772
2020	678
2021	630
2022	583
Thereafter	27,139
Total	$ 31,297	[1]

[1] Minimum rental payments have not been reduced by minimum sublease rentals of $783 due in the future under non-cancelable subleases.