Leases - Maturities of remaining operating lease liabilities (Details)	Mar. 31, 2019 USD ($)
Maturity of remaining operating lease liabilities:
2019 (excluding the 1st quarter ending March 31, 2019)	$ 227,000
2020	305,000
2021	308,000
2022	310,000
2023	312,000
Thereafter	1,345,000
Total lease payments	2,807,000
Less imputed interest	(460,000)
Total lease liabilities, as reported	2,347,000
Operating lease not yet commenced amount	$ 58,000