Leases - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) option	Mar. 31, 2018 USD ($)
Lessor, Lease, Description [Line Items]
Number of extension options (option) | option	1
Lessee, operating lease, renewal term (years)	10 years
Right-of-use asset	$ 4,928
Lease liability	$ 5,284
Weighted average discount rate (percentage)	4.20%
Operating leases, rent expense	$ 186	$ 186
Cash paid for rent expense	$ 200	$ 200
Minimum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)	5 years
Maximum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)	25 years
Alexander Apartment Tower | Minimum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)	1 year
Alexander Apartment Tower | Maximum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)	2 years