Long-Term Debt - Mortgages (Narrative) (Details) - USD ($)	1 Months Ended
	Mar. 31, 2020	Nov. 30, 2019	Jan. 31, 2021
Bond St. Building Brooklyn NY Two [Member]
Debt Instrument [Line Items]
Debt instrument face amount		$ 5,255,920
Additional loans		144,080
Amount outstanding		$ 5,400,000
Term of loan		5 years
Interest rate, percent		4.375%	4.375%	[1]
Bond St. Building Brooklyn NY Two [Member] | Another Bank [Member]
Debt Instrument [Line Items]
Debt instrument face amount		$ 6,000,000
Interest rate, percent		3.54%
Fishkill, New York Property [Member]
Debt Instrument [Line Items]
Debt instrument face amount	$ 4,000,000
Term of loan	20 years
Maturity period of loan	5 years
Interest rate, percent	3.98%		3.98%	[2]

[1] In November 2019, the Company refinanced the remaining balance of a $6,000,000, 3.54% interest rate loan with another bank for $5,255,920 plus an additional $144,080 for a total of $5,400,000. The interest rate on the new loan is fixed at 4.375%. The loan is self-liquidating over a period of five years and secured by the Nine Bond Street building in Brooklyn, New York.

[2] In March 2020, the Company obtained a loan with a bank in the amount of $4,000,000 to finance renovations and brokerage commissions relating to space leased to a community college at the Fishkill, New York building. The loan is secured by the Fishkill, New York building; amortized over a 20-year period with an interest rate of 3.98% and is due in five years.