Leases - Lessee Accounting (Details)	9 Months Ended
	Sep. 30, 2020 USD ($) contract	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Right-of-use asset	$ 2,701,000	$ 2,822,000	$ 2,900,000
Lease liability	$ 2,720,000	$ 2,833,000	$ 2,900,000
Ground Lease | Yonkers, NY
Lessee, Lease, Description [Line Items]
Number of contracts | contract	1
Renewal term option	21 years
Remaining term	25 years
Ground Lease | Great Neck, NY
Lessee, Lease, Description [Line Items]
Remaining term	16 years 3 months 18 days
Corporate Office | Great Neck, NY
Lessee, Lease, Description [Line Items]
Renewal term option	5 years