Leases - Lessor Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lessor, Lease, Description [Line Items]
Revenues	$ 206,148	$ 199,142	$ 226,350
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
The Alexander apartment tower | Minimum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)	1 year
The Alexander apartment tower | Maximum
Lessor, Lease, Description [Line Items]
Lessor, operating lease, term (years)	2 years
Revenue Benchmark | Bloomberg | Customer Concentration Risk
Lessor, Lease, Description [Line Items]
Revenues	$ 113,140	$ 109,066	$ 109,113
Percentage rent contributed by tenant	55.00%	55.00%	48.00%